Science.gov

Sample records for binary acetonitrile-water mixtures

  1. Study of Microheterogeneity in Acetonitrile-Water Binary Mixtures by using Polarity-Resolved Solvation Dynamics.

    PubMed

    Koley, Somnath; Ghosh, Subhadip

    2015-11-16

    The solvation dynamics of three coumarin dyes with widely varying polarities were studied in acetonitrile-water (ACN-H2O) mixtures across the entire composition range. At low ACN concentrations [ACN mole fractions (X(ACN))≤0.1], the solvation dynamics are fast (<40 ps), indicating a nearly homogeneous environment. This fast region is followed by a sudden retardation of the average solvation time (230-1120 ps) at higher ACN concentrations (X(ACN)≈0.2), thus indicating the onset of nonideality within the mixture that continues until X(ACN)≈0.8. This nonideality regime (X(ACN)≈0.2-0.8) comprises of multiple dye-dependent anomalous regions. At very high ACN concentrations (X(ACN)≈0.8-1), the ACN-H2O mixtures regain homogeneity, with faster solvation times. The source of the inherent nonideality of the ACN-H2O mixtures is a subject of debate. However, a careful examination of the widths of time-resolved emission spectra shows that the origin of the slow dynamics may be due to the diffusion of polar solvent molecules into the first solvation shell of the excited coumarin dipole.

  2. Structure-retention and mobile phase-retention relationships for reversed-phase high-performance liquid chromatography of several hydroxythioxanthone derivatives in binary acetonitrile-water mixtures.

    PubMed

    Amiri, Ali Asghar; Hemmateenejad, Bahram; Safavi, Afsaneh; Sharghi, Hashem; Beni, Ali Reza Salimi; Shamsipur, Mojtaba

    2007-12-12

    The reversed-phase high-performance liquid chromatographic (RP-HPLC) behavior of some newly synthesized hydroxythioxanthone derivatives using binary acetonitrile-water mixtures as mobile phase has been examined. First, the variation in the retention time of each molecule as a function of mobile phase properties was studied by Kamlet-Taft solvatochromic equations. Then, the influences of molecular structure of the hydroxythioxanthone derivatives on their retention time in various mobile phase mixtures were investigated by quantitative structure-property relationship (QSPR) analysis. Finally, a unified model containing both the molecular structure parameters and mobile phase properties was developed to describe the chromatographic behavior of the systems studied. Among the solvent properties, polarity/polarizability parameter (pi*) and hydrogen-bond basicity (beta), and among the solute properties, the most positive local charge (MPC), the sum of positive charges on hydrogen atoms contributing in hydrogen bonding (SPCH) and lipophilicity index (logP) were identified as controlling factors in the RP-HPLC behavior of hydroxythioxanthone derivatives in actonitrile-water binary solvents.

  3. Reversed-phase high performance liquid chromatography (RP-HPLC) characteristics of some 9,10-anthraquinone derivatives using binary acetonitrile-water mixtures as mobile phase.

    PubMed

    Hemmateenejad, B; Shamsipur, M; Safavi, A; Sharghi, H; Amiri, A A

    2008-10-19

    The retention behavior of 28 synthesized 9,10-anthraquinone derivatives in a reversed-phase (RP) high performance liquid chromatography (HPLC) system has been studied on a C18-RP column using acetonitrile-water mixtures as mobile phase. The influences of the composition of mobile phase and the solute structure on the retention times of 9,10-anthraquinone derivatives were investigated by linear solvation free energy relationship (LSFER) and quantitative structure-retention relationship (QSRR) analyses. Among different solvatochromic parameters of solvent systems, their polarity/polarizability parameter (pi*) was identified as the controlling factor affecting retention behavior of these compounds. A four-parametric QSRR model was obtained between solute structures and retention indices. Finally, a unified model containing both the molecular structure parameters and mobile phase properties was developed to describe the chromatographic behavior of the systems studied. The resulted QSRR models could explain and predict higher than 90% of variances in the retention indices. Among the solvent properties, polarity/polarizability parameter (pi*), and among the solute properties, HATS5v (leverage-weighted autocorrelation of lag 5/weighted by atomic van der Waals volumes, GETAWAY descriptors), Mor14p (3D-MoRSE-signal 14/weighted by atomic polarizabilities, 3D-MoRSE descriptors), GATS5p (Geary autocorrelation-lag 5/weighted by atomic polarizabilities, 2D autocorrelations) and R6u+(R maximal autocorrelation of lag 6/unweighted, GETAWAY descriptors) were identified as controlling factors in the RP-HPLC behavior of 9,10-anthraquinone derivatives in actonitrile-water binary solvents.

  4. A deeper insight into an intriguing acetonitrile-water binary mixture: synergistic effect, dynamic Stokes shift, fluorescence correlation spectroscopy, and NMR studies.

    PubMed

    Koley, Somnath; Ghosh, Subhadip

    2016-11-30

    An insight study reveals the strong synergistic solvation behaviours from reporter dye molecules within the acetonitrile (ACN)-water (WT) binary mixture. Synergism of a binary mixture refers to some unique changes of the physical and thermodynamic properties of the solvent mixture, originating from the interactions among its cosolvents, which are absent within the pure cosolvents. Synergistic solvation of a binary mixture is likely to be fundamental for greater stabilization of an excited state solute dipole; at least to some extent greater as compared to one stabilized by any of its cosolvents alone. A dynamic Stokes shift due to the solvation of an excited dipole in the ACN-WT binary mixture is found to be highly relevant to the ground state physical properties of the solute molecule (polarity, hydrophilicity, acidity, etc.). Largely different solvation times in the ACN-WT mixture are observed from different dye molecules with widely varying polarities. However, earlier study shows that dye molecules, irrespective of their varying polarities, exhibit very similar solvation times within a pure solvent (J. Phys. Chem. B, 2014, 118, 7577-7785). On further study with fluorescence correlation spectroscopy (FCS) we observed that, unlike the translational diffusion coefficient (Dt) of a dye molecule within a pure solvent, which remains the same irrespective of the location of the dye molecule inside the solvent, a broad distribution among the Dt values of a dye molecule is obtained from different locations within the ACN-WT binary mixture. Lastly our (1)H NMR study in the ACN-WT binary mixture shows the existence of strong hydrogen bond interactions among the cosolvents in the ACN-WT mixture.

  5. Persistence of acetonitrile bilayers at the interface of acetonitrile/water mixtures with silica.

    PubMed

    Rivera, Christopher A; Bender, John S; Manfred, Katherine; Fourkas, John T

    2013-11-21

    Previous experiments and simulations have shown that acetonitrile organizes into a lipid-like bilayer at the liquid/silica interface. Recent simulations have further suggested that this bilayer structure persists in mixtures of acetonitrile with water, even at low acetonitrile concentrations. This behavior is indicative of microscopic phase separation of these liquids near silica interfaces and may have important ramifications for the use of acetonitrile in chromatography and heterogeneous catalysis. To explore this phenomenon, we have used vibrational sum-frequency-generation spectroscopy to probe acetonitrile/water mixtures at a silica interface. Our spectra provide evidence that acetonitrile partitions to the hydrated silica interface even when the mole fraction of acetonitrile is as low as 10%. A blue shift is observed in the spectrum of the methyl symmetric stretch upon increasing water mole fraction, in agreement with vibrational spectra of bulk mixtures. Line shape analysis suggests that acetonitrile may exist in the form of bilayer patches at high water mole fractions.

  6. Ab initio study of the structural properties of acetonitrile-water mixtures

    NASA Astrophysics Data System (ADS)

    Chen, Jinfan; Sit, Patrick H.-L.

    2015-08-01

    Structural properties of acetonitrile and acetonitrile-water mixtures are studied using Density Functional Theory (DFT) and ab initio molecular dynamics simulations. Stable molecular clusters consisted of several water and acetonitrile molecules are identified to provide microscopic understanding of the interaction among water and acetonitrile molecules. Ab initio molecular dynamics simulations are performed to study the liquid structure at the finite temperature. Three mixing compositions in which the mole fraction of acetonitrile equals 0.109, 0.5 and 0.891 are studied. These compositions correspond to three distinct structural regimes. At the 0.109 and 0.891 mole fraction of acetonitrile, the majority species are mostly connected among themselves and the minority species are either isolated or forming small clusters without disrupting the network of the majority species. At the 0.5 mole fraction of acetonitrile, large water and acetonitrile clusters persist throughout the simulation, exhibiting the microheterogeneous behavior in acetonitrile-water mixtures in the mid-range mixing ratio.

  7. Electrochemical detection of benzo(a)pyrene in acetonitrile-water binary medium.

    PubMed

    Du, Chunyan; Hu, Yaqi; Li, Yunchao; Fan, Louzhen; Li, Xiaohong

    2015-06-01

    Electrochemical oxidation of adsorbed benzo(a)pyrene (BaP) on the glassy carbon electrode (GCE) was explored in acetonitrile-water. When the GCE was incubated in 100 nM BaP acetonitrile-water (V(water):V(acetonitrile)=1:1) for 10 min at open circuit, and then transferred into blank acetonitrile-water (V(water):V(acetonitrile)=1:1, pH= 0.70) for differential pulse voltammetry measurement, a distinct oxidation peak at 0.98 V (vs. Ag/AgCl) was observed. The peak potential was about 180 mV lower than that in acetonitrile. Importantly, the peak current was more than 22 times greater. The effects of water on BaP preconcentration on the electrode and electrochemical oxidation were revealed, respectively. Based on the results, an electrochemical assay for BaP detection was developed. The GCE was respectively incubated in acetonitrile-water (V(water):V(acetonitrile)=1:1)with BaP concentration ranged from 0 nM to 1000 nM, and then transferred into the corresponding blank acetonitrile-water (pH= 0.70) for DPV measurements. When the BaP concentration was increased, an increased oxidative current at 0.98 V (vs. Ag/AgCl) was observed, and a detection limit of 0.67 nM was achieved. Because all other priority polycyclic aromatic hydrocarbons could not be electrochemically oxidized at 0.98 V, the electrochemical assay showed very high selectivity to BaP. Finally, the developed electrochemical assay was successfully applied to determination of BaP in a series of real world samples, such as drinking water, tap water, lake water and river water.

  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. Viscosity measurements of methanol-water and acetonitrile-water mixtures at pressures up to 3500 bar using a novel capillary time-of-flight viscometer.

    PubMed

    Thompson, J Will; Kaiser, Theodore J; Jorgenson, James W

    2006-11-17

    A new type of viscometer based on the Poiseuille flow principle has been developed that is capable of measuring solution viscosities at ultrahigh pressures. The capillary time-of-flight (CTOF) viscometer has been used to measure the viscosity of methanol-water and acetonitrile-water mixtures in decade volume% increments from atmospheric pressure to 3500 bar (50,000 psi), at 25 degrees C. This instrument works by utilizing a relatively small pressure drop (approximately 200 bar) across a capillary which has both inlet and outlet pressurized so that the average column pressure can be significantly elevated (up to 3500 bar). Measurements from the CTOF viscometer match high-pressure viscosity data collected previously using falling-body viscometers of the Bridgman design. This manuscript serves to bring viscosity data at ultrahigh pressures for the two most common liquid chromatographic mobile phases into the chromatographic literature.

  10. Automatized sspKa measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60°C.

    PubMed

    Acquaviva, A; Tascon, M; Padró, J M; Gagliardi, L G; Castells, C B

    2014-09-01

    We measured pKa values of Tris(hydroxymethyl)aminomethane and dihydrogen phosphate; both are commonly used to prepare buffers for reverse-phase liquid chromatography (RPLC), in acetonitrile/water mixtures from 0% to 70% (v/v) (64.6% (w/w)) acetonitrile and at 20, 30, 40, 50, and 60°C. The procedure is based on potentiometric measurements of pH of buffer solutions of variable solvent compositions using a glass electrode and a novel automated system. The method consists in the controlled additions of small volumes of a thermostated solution from an automatic buret into another isothermal solution containing exactly the same buffer-component concentrations, but a different solvent composition. The continuous changes in the solvent composition induce changes in the potentials. Thus, only two sequences of additions are needed: increasing the amount of acetonitrile from pure water and decreasing the content of acetonitrile from 70% (v/v) (64.6% (w/w)). In the procedure with homemade apparatus, times for additions, stirring, homogenization, and data acquisition are entirely controlled by software programmed for this specific routine. This rapid, fully automated method was applied to acquire more than 40 potential data covering the whole composition range (at each temperature) in about two hours and allowed a systematic study of the effect of temperature and acetonitrile composition on acid-base equilibria of two widely used substances to control pH close to 7. The experimental pKa results were fitted to empirical functions between pKa and temperature and acetonitrile composition. These equations allowed predictions of pKa to estimate the pH of mixtures at any composition and temperature, which would be very useful, for instance, during chromatographic method development.

  11. Determination of the solvent density profiles across mesopores of silica-C18 bonded phases in contact with acetonitrile/water mixtures: A semi-empirical approach.

    PubMed

    Gritti, Fabrice

    2015-09-04

    The local volume fractions of water, acetonitrile, and C18-bonded chains across the 96Åmesopores of 5μm Symmetry particles were determined semi-empirically. The semi-empirical approach was based on previous molecular dynamics studies, which provided relevant mathematical expressions for the density profiles of C18 chains and water molecules, and on minor disturbance experiments, which measured the excess amount of acetonitrile adsorbed in the pores of Symmetry-C18 particles. The pore walls of the Symmetry-C18 material were in thermodynamic equilibrium with a series of binary mixtures of water and acetonitrile. The results show that C18 chains are mostly solvated by acetonitrile molecules, water is excluded from the C18-bonded layer, and acetonitrile concentrates across a 15-25Åthick interface region between the C18 layer and the bulk phase. These actual density profiles are expected to have a direct impact on the retention behaviour of charged, polar, and neutral analytes in RPLC. They also provide clues to predict the local mobility of analytes inside the pores and a sound physico-chemical description of the phenomenon of surface diffusion observed in RPLC.

  12. Marangoni convection in binary mixtures.

    PubMed

    Zhang, Jie; Behringer, Robert P; Oron, Alexander

    2007-07-01

    Marangoni instabilities in binary mixtures in the presence of the Soret effect and evaporation are different from those in pure liquids. In contrast to a large amount of experimental work on Marangoni convection in pure liquids, such experiments in binary mixtures are not available in the literature, to our knowledge. Using binary mixtures of NaCl/water in an open system, evaporation of water molecules at the liquid-vapor interface is inevitable. We have systematically investigated the pattern formation for a set of substrate temperatures and solute concentrations in an open system. The flow patterns evolve with time, driven by surface-tension fluctuations due to evaporation and the Soret effect, while the air-liquid interface does not deform. A shadow-graph method is used to follow the pattern formation in time. The patterns are mainly composed of polygons and rolls. The mean pattern size first decreases slightly, and then gradually increases during the evolution. Evaporation affects the pattern formation mainly at the early stages and the local evaporation rate tends to become spatially uniform at the film surface. The Soret effect becomes important at the later stages and affects the mixture for a large mean solute concentration where the Soret number is significantly above zero. The strength of convection increases with the initial solute concentration and the substrate temperature. Our findings differ from the theoretical predictions in which evaporation is neglected.

  13. Interdiffusion in binary ionic mixtures

    SciTech Connect

    Boercker, D.B.; Pollock, E.L.

    1987-08-15

    In this paper we present molecular-dynamics and kinetic-theory calculations of the interdiffusion coefficients in dense binary ionic mixtures for conditions appropriate to both astrophysical and inertial-confinement fusion (ICF) plasmas. The diffusion coefficient is the product of a Green-Kubo integral and a thermodynamic prefactor. The molecular-dynamics and kinetic-theory estimates of the Green-Kubo portion agree very well, and it is found that this integral may also be well represented by the usual concentration-weighted sum of self-diffusion coefficients. In addition, the low-density limit of the thermodynamic prefactor is shown to represent an enhancement of the diffusion by the ''ambipolar'' electric field.

  14. Synthesis of nano-sized hydrogen phosphate-imprinted polymer in acetonitrile/water mixture and its use as a recognition element of hydrogen phosphate selective all-solid state potentiometric electrode.

    PubMed

    Alizadeh, Taher; Atayi, Khalil

    2017-10-10

    Herein, a new recipe is introduced for the preparation of hydrogen phosphate ion-imprinted polymer nanoparticles (nano-IIP) in acetonitrile/water (63.5:36.5) using phosphoric acid as the template. The nano-IIP obtained was used as the recognition element of a carbon paste potentiometric sensor. The IIP electrode showed a Nernstian response to hydrogen phosphate anion; whereas, the non-imprinted polymer (NIP)-based electrode had no considerable sensitivity to the anion. The presence of both methacrylic acid and vinyl pyridine in the IIP structure, as well as optimization of the functional monomers-template proportion, was found to be important to observe the sensing capability of the IIP electrode. The nano-IIP electrode showed a dynamic linear range of 1 × 10(-5) -1 × 10(-1)  mol L-1, Nernstian slope of 30.6 ± (0.5) mV decade (-1) , response time of 25 seconds, and detection limit of 4.0 × 10(-6)  mol L(-1) . The utility of the electrodes was checked by potentiometric titration of hydrogen phosphate with La(3+) solution. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Silo discharge of binary granular mixtures.

    PubMed

    Madrid, M; Asencio, K; Maza, D

    2017-08-01

    We present numerical and experimental results on the mass flow rate during the discharge of three-dimensional silos filled with a bidisperse mixture of grains of different sizes. We analyzed the influence of the ratio between coarse and fine particles on the profile of volume fraction and velocity across the orifice. By using numerical simulations, we have shown that the velocity profile has the same shape as that in the monodisperse case and is insensitive to the composition of the mixture. On the contrary, the volume fraction profile is strongly affected by the composition of the mixture. Assuming that an effective particle size can be introduced to characterize the mixture, we have shown that previous expression for the mass flow rate of monodisperse particles can be used for binary mixtures. A comparison with Beverloo's correlation is also presented.

  16. Spinodal decomposition of chemically reactive binary mixtures

    NASA Astrophysics Data System (ADS)

    Lamorgese, A.; Mauri, R.

    2016-08-01

    We simulate the influence of a reversible isomerization reaction on the phase segregation process occurring after spinodal decomposition of a deeply quenched regular binary mixture, restricting attention to systems wherein material transport occurs solely by diffusion. Our theoretical approach follows a diffuse-interface model of partially miscible binary mixtures wherein the coupling between reaction and diffusion is addressed within the frame of nonequilibrium thermodynamics, leading to a linear dependence of the reaction rate on the chemical affinity. Ultimately, the rate for an elementary reaction depends on the local part of the chemical potential difference since reaction is an inherently local phenomenon. Based on two-dimensional simulation results, we express the competition between segregation and reaction as a function of the Damköhler number. For a phase-separating mixture with components having different physical properties, a skewed phase diagram leads, at large times, to a system converging to a single-phase equilibrium state, corresponding to the absolute minimum of the Gibbs free energy. This conclusion continues to hold for the critical phase separation of an ideally perfectly symmetric binary mixture, where the choice of final equilibrium state at large times depends on the initial mean concentration being slightly larger or less than the critical concentration.

  17. Capillary condensation and adsorption of binary mixtures.

    PubMed

    Weinberger, B; Darkrim-Lamari, F; Levesque, D

    2006-06-21

    The adsorption of equimolar binary mixtures of hydrogen-carbon dioxide, hydrogen-methane, and methane-carbon dioxide in porous material models is determined by grand canonical Monte Carlo simulations. The material models have an adsorbent surface similar to that of nanofibers with a herringbone structure. Our main result, which is relevant for hydrogen purification and carbon dioxide capture, is that the adsorption selectivities calculated for the mixtures can differ significantly from those deduced from simulations of the adsorption of pure gases, in particular, when one of the adsorbed gases presents a capillary condensation induced by confinement within the pore network. A comparison of our data is also made with theoretical models used in the literature for predicting the properties of the mixture adsorption.

  18. Pycnonuclear reaction rates for binary ionic mixtures

    NASA Technical Reports Server (NTRS)

    Ichimaru, S.; Ogata, S.; Van Horn, H. M.

    1992-01-01

    Through a combination of compositional scaling arguments and examinations of Monte Carlo simulation results for the interparticle separations in binary-ionic mixture (BIM) solids, we have derived parameterized expressions for the BIM pycnonuclear rates as generalizations of those in one-component solids obtained previously by Salpeter and Van Horn and by Ogata et al. We have thereby discovered a catalyzing effect of the heavier elements, which enhances the rates of reactions among the lighter elements when the charge ratio exceeds a critical value of approximately 2.3.

  19. Pycnonuclear reaction rates for binary ionic mixtures

    NASA Technical Reports Server (NTRS)

    Ichimaru, S.; Ogata, S.; Van Horn, H. M.

    1992-01-01

    Through a combination of compositional scaling arguments and examinations of Monte Carlo simulation results for the interparticle separations in binary-ionic mixture (BIM) solids, we have derived parameterized expressions for the BIM pycnonuclear rates as generalizations of those in one-component solids obtained previously by Salpeter and Van Horn and by Ogata et al. We have thereby discovered a catalyzing effect of the heavier elements, which enhances the rates of reactions among the lighter elements when the charge ratio exceeds a critical value of approximately 2.3.

  20. Excess compressibility in binary liquid mixtures.

    PubMed

    Aliotta, F; Gapiński, J; Pochylski, M; Ponterio, R C; Saija, F; Salvato, G

    2007-06-14

    Brillouin scattering experiments have been carried out on some mixtures of molecular liquids. From the measurement of the hypersonic velocities we have evaluated the adiabatic compressibility as a function of the volume fraction. We show how the quadratic form of the excess compressibility dependence on the solute volume fraction can be derived by simple statistical effects and does not imply any interaction among the components of the system other than excluded volume effects. This idea is supported by the comparison of the experimental results with a well-established prototype model, consisting of a binary mixture of hard spheres with a nonadditive interaction potential. This naive model turns out to be able to produce a very wide spectrum of structural and thermodynamic features depending on values of its parameters. An attempt has made to understand what kind of structural information can be gained through the analysis of the volume fraction dependence of the compressibility.

  1. Dynamic thermodiffusion model for binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Eslamian, Morteza; Saghir, M. Ziad

    2009-07-01

    Following the nonequilibrium thermodynamics approach, we develop a dynamic model to emulate thermo-diffusion process and propose expressions for estimating the thermal diffusion factor in binary nonassociating liquid mixtures. Here, we correlate the net heat of transport in thermodiffusion with parameters, such as the mixture temperature and pressure, the size and shape of the molecules, and mobility of the components, because the molecules have to become activated before they can move. Based on this interpretation, the net heat of transport of each component can be somehow related to the viscosity and the activation energy of viscous flow of the same component defined in Eyring’s reaction-rate theory [S. Glasstone, K. J. Laidler, and H. Eyring, The Theory of Rate Processes: The Kinetics of Chemical Reactions, Viscosity, Diffusion and Electrochemical Phenomena (McGraw-Hill, New York, 1941)]. This modeling approach is different from that of Haase and Kempers, in which thermodiffusion is considered as a function of the thermostatic properties of the mixture such as enthalpy. In simulating thermodiffusion, by correlating the net heat of transport with the activation energy of viscous flow, effects of the above mentioned parameters are accounted for, to some extent of course. The model developed here along with Haase-Kempers and Drickamer-Firoozabadi models linked with the Peng-Robinson equation of sate are evaluated against the experimental data for several recent nonassociating binary mixtures at various temperatures, pressures, and concentrations. Although the model prediction is still not perfect, the model is simple and easy to use, physically justified, and predicts the experimental data very good and much better than the existing models.

  2. Dynamic thermodiffusion model for binary liquid mixtures.

    PubMed

    Eslamian, Morteza; Saghir, M Ziad

    2009-07-01

    Following the nonequilibrium thermodynamics approach, we develop a dynamic model to emulate thermo-diffusion process and propose expressions for estimating the thermal diffusion factor in binary nonassociating liquid mixtures. Here, we correlate the net heat of transport in thermodiffusion with parameters, such as the mixture temperature and pressure, the size and shape of the molecules, and mobility of the components, because the molecules have to become activated before they can move. Based on this interpretation, the net heat of transport of each component can be somehow related to the viscosity and the activation energy of viscous flow of the same component defined in Eyring's reaction-rate theory [S. Glasstone, K. J. Laidler, and H. Eyring, (McGraw-Hill, New York, 1941)]. This modeling approach is different from that of Haase and Kempers, in which thermodiffusion is considered as a function of the thermostatic properties of the mixture such as enthalpy. In simulating thermodiffusion, by correlating the net heat of transport with the activation energy of viscous flow, effects of the above mentioned parameters are accounted for, to some extent of course. The model developed here along with Haase-Kempers and Drickamer-Firoozabadi models linked with the Peng-Robinson equation of sate are evaluated against the experimental data for several recent nonassociating binary mixtures at various temperatures, pressures, and concentrations. Although the model prediction is still not perfect, the model is simple and easy to use, physically justified, and predicts the experimental data very good and much better than the existing models.

  3. ThermoData Engine Database - Pure Compounds and Binary Mixtures

    National Institute of Standards and Technology Data Gateway

    SRD 103b NIST ThermoData Engine Version 6.0 - Pure CompoThermoData Engine Database - Pure Compounds and Binary Mixtures (PC database for purchase)   This database contains property data for more than 21,000 pure compounds, 37,500 binary mixtures, 10,000 ternary mixtures, and 6,000 chemical reactions.

  4. Phase equilibrium measurements on twelve binary mixtures

    SciTech Connect

    Giles, N.F.; Wilson, H.L.; Wilding, W.V.

    1996-11-01

    Phase equilibrium measurements have been performed on twelve binary mixtures. The PTx method was used to obtain vapor-liquid equilibrium data for the following binary systems at two temperatures each: ethanethiol + propylene; nitrobenzene + methanol; pyridine + ethyl acetate; octane + tert-amyl methyl ether; diisopropyl ether + butane; 1,3-dichloro-2-propanol + epichlorohydrin; 2,3-dichloro-1-propanol + epichlorohydrin; 2,3-epoxy-1-propanol + epichlorohydrin; 3-chloro-1,2-propanediol + epichlorohydrin; methanol + hydrogen cyanide. For these systems, equilibrium vapor and liquid phase compositions were derived from the PTx data using the Soave equation of state to represent the vapor phase and the Wilson, NRTL, or Redlich-Kister activity coefficient model to represent the liquid phase. The infinite dilution activity coefficient of methylamine in N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone-rich half of the binary. Liquid-liquid equilibrium studies were made on the triethylene glycol + 1-pentene system at two temperatures by directly analyzing samples taken from each liquid phase.

  5. Microscopic Hydrodynamic Modes in a Binary Hard Sphere Mixture

    NASA Astrophysics Data System (ADS)

    Reichl, L. E.; Gust, Erich D.

    2017-07-01

    We derive analytic microscopic expressions for the shear viscosity, the speed of sound, and the decay rates of the hydrodynamic modes in a hard sphere binary gas mixture directly from the spectral properties of coupled Boltzmann equations. We show that the analytic expressions give good agreement with experimental viscosity data and to the results of light scattering experiments on noble gas binary mixtures.

  6. Hydrodynamic 'memory' of binary fluid mixtures

    SciTech Connect

    Kalashnik, M. V.; Ingel, L. Kh.

    2006-07-15

    A theoretical analysis is presented of hydrostatic adjustment in a two-component fluid system, such as seawater stratified with respect to temperature and salinity. Both linear approximation and nonlinear problem are investigated. It is shown that scenarios of relaxation to a hydrostatically balanced state in binary fluid mixtures may substantially differ from hydrostatic adjustment in fluids that can be stratified only with respect to temperature. In particular, inviscid two-component fluids have 'memory': a horizontally nonuniform disturbance in the initial temperature or salinity distribution does not vanish even at the final stage, transforming into a persistent thermohaline 'trace.' Despite stability of density stratification and convective stability of the fluid system by all known criteria, an initial temperature disturbance may not decay and may even increase in amplitude. Moreover, its sign may change (depending on the relative contributions of temperature and salinity to stable background density stratification). Hydrostatic adjustment may involve development of discontinuous distributions from smooth initial temperature or concentration distributions. These properties of two-component fluids explain, in particular, the occurrence of persistent horizontally or vertically nonuniform temperature and salinity distributions in the ocean, including discontinuous ones.

  7. Thermodiffusion in binary and ternary nonpolar hydrocarbon + alcohol mixtures

    NASA Astrophysics Data System (ADS)

    Eslamian, Morteza; Saghir, M. Ziad

    2012-12-01

    Thermodiffusion in complex mixtures, such as associating, molten metal, and polymer mixtures is difficult to model usually owing to the occurrence of a sign change in the thermodiffusion coefficient when the mixture concentration and temperature change. A mixture comprised of a nonpolar hydrocarbon and an alcohol is a complex and highly non-ideal mixture. In this paper an existing binary non-equilibrium thermodynamics model (Eslamian and Saghir, Physical Review E 80, 061201, 2009) developed for aqueous mixtures of alcohols is examined against the experimental data of binary nonpolar hydrocarbon and alcohol mixtures. For ternary mixtures, non-equilibrium thermodynamic expressions developed by the authors for aqueous mixtures of alcohols (Eslamian and Saghir, Canadian Journal of Chemical Engineering, DOI 10.1002/cjce.20581) is used to predict thermodiffusion coefficients of ternary nonpolar hydrocarbon and alcohol mixtures. The rationale behind the sign change is elucidated and attributed to an anomalous change in the molecular structure and therefore viscosity of such mixtures. Model predictions of thermodiffusion coefficients of binary mixtures predict a sign change consistent with the experimental data although the model is still too primitive to capture all structural complexities. For instance, in the methanol-benzene mixture where the model predictions are poorest, the viscosity data show that when concentration varies, the mixture's molecular structure experiences a severe change twice, the first major change leading to a maximum in the thermodiffusion coefficient, whereas the second change causes a sign change.

  8. Importance of Molecular Structure on the Thermophoresis of Binary Mixtures.

    PubMed

    Kumar, Pardeep; Goswami, Debabrata

    2014-12-26

    Using thermal lens spectroscopy, we study the role of molecular structural isomers of butanol on the thermophoresis (or Soret effect) of binary mixtures of methanol in butanol. In this study, we show that the thermal lens signal due to the Soret effect changes its sign for all the different concentrations of binary mixtures of butanol with methanol except for the one containing tertiary-butanol. The magnitude and sign of the Soret coefficients strongly depend on the molecular structure of the isomers of butanol in the binary mixture with methanol. This isomerization dependence is in stark contrast to the expected mass dependence of the Soret effect.

  9. 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

  10. Evolution of weak disturbances in inert binary mixtures

    NASA Technical Reports Server (NTRS)

    Rasmussen, M. L.

    1977-01-01

    The evolution of weak disturbances in inert binary mixtures is determined for the one-dimensional piston problem. The interaction of the dissipative and nonlinear mechanisms is described by Burgers' equation. The binary mixture diffusion mechanisms enter as an additive term in an effective diffusivity. Results for the impulsive motion of a piston moving into an ambient medium and the sinusoidally oscillating piston are used to illustrate the results and elucidate the incorrect behavior pertaining to the associated linear theory.

  11. Simulation of binary mixtures with the lattice Boltzman method.

    PubMed

    Arcidiacono, S; Mantzaras, J; Ansumali, S; Karlin, I V; Frouzakis, C; Boulouchos, K B

    2006-11-01

    A lattice Boltzman model for the simulation of binary mixtures is presented. Contrary to previous models, the present formulation is able to simulate mixtures with different Schmidt numbers and arbitrary molecular mass ratio of the components. In the hydrodynamic limit, the Navier-Stokes and the Stefan-Maxwell binary diffusion equations are recovered. The model is used for the simulation of binary diffusion and mixing layers. The results are found to be in good agreement with a derived similarity solution and with the predictions of a transient spectral element code.

  12. Solubility enhancement of miconazole nitrate: binary and ternary mixture approach.

    PubMed

    Rai, Vineet Kumar; Dwivedi, Harinath; Yadav, Narayan Prasad; Chanotiya, Chandan Singh; Saraf, Shubhini A

    2014-08-01

    Enhancement of aqueous solubility of very slightly soluble Miconazole Nitrate (MN) is required to widen its application from topical formulation to oral/mucoadhesive formulations. Aim of the present investigation was to enhance the aqueous solubility of MN using binary and ternary mixture approach. Binary mixtures such as solvent deposition, inclusion complexation and solid dispersion were adopted to enhance solubility using different polymers like lactose, beta-cyclodextrin (β-CD) and polyethylene-glycol 6000 (PEG 6000), respectively. Batches of binary mixtures with highest solubility enhancement potentials were further mixed to form ternary mixture by a simple kneading method. Drug polymer interaction and mixture morphology was studied using the Fourier transform infrared spectroscopy and the scanning electron microscopy, respectively along with their saturation solubility studies and drug release. An excellent solubility enhancement, i.e. up to 72 folds and 316 folds of MN was seen by binary and ternary mixture, respectively. Up to 99.5% drug was released in 2 h from the mixtures of MN and polymers. RESULTS revealed that solubility enhancement by binary mixtures is achieved due to surface modification and by increasing wettability of MN. Tremendous increase in solubility of MN by ternary mixture could possibly be due to blending of water soluble polymers, i.e. lactose and PEG 6000 with β-CD which was found to enhance the solubilizing nature of β-CD. Owing to the excellent solubility enhancement potential of ternary mixtures in enhancing MN solubility from 110.4 μg/ml to 57640.0 μg/ml, ternary mixture approach could prove to be promising in the development of oral/mucoadhesive formulations.

  13. Widom Lines in Binary Mixtures of Supercritical Fluids.

    PubMed

    Raju, Muralikrishna; Banuti, Daniel T; Ma, Peter C; Ihme, Matthias

    2017-06-08

    Recent experiments on pure fluids have identified distinct liquid-like and gas-like regimes even under supercritical conditions. The supercritical liquid-gas transition is marked by maxima in response functions that define a line emanating from the critical point, referred to as Widom line. However, the structure of analogous state transitions in mixtures of supercritical fluids has not been determined, and it is not clear whether a Widom line can be identified for binary mixtures. Here, we present first evidence for the existence of multiple Widom lines in binary mixtures from molecular dynamics simulations. By considering mixtures of noble gases, we show that, depending on the phase behavior, mixtures transition from a liquid-like to a gas-like regime via distinctly different pathways, leading to phase relationships of surprising complexity and variety. Specifically, we show that miscible binary mixtures have behavior analogous to a pure fluid and the supercritical state space is characterized by a single liquid-gas transition. In contrast, immiscible binary mixture undergo a phase separation in which the clusters transition separately at different temperatures, resulting in multiple distinct Widom lines. The presence of this unique transition behavior emphasizes the complexity of the supercritical state to be expected in high-order mixtures of practical relevance.

  14. Calculation of the viscosity of binary liquid mixtures

    SciTech Connect

    Nadirov, N.K.; Urazgaliev, B.U.; Ni, E.A.

    1986-11-01

    The authors construct an equation for the kinematic viscosity of binary petroleum mixtures which incorporates the dependence of this property on temperature and hydrocarbon composition and density. The equation is applied to crudes and their mixtures from the Kalamkas and karazhanbas fields in the Soviet Union.

  15. Nonergodic correction to a binary mixture phase diagram

    NASA Astrophysics Data System (ADS)

    Son, L.

    2016-05-01

    For a binary mixture with limited miscibility of the components, the correction to the equation of state that arises from the finite diffusion velocity is discussed. It is shown that this correction corresponds to a nonergodic microheterogeneity of the mixture. We suggest that the above microheterogeneity may be accounted as corresponding fluctuations of the chemical potential. The mean square of these fluctuations C is an additional thermodynamic variable, and the nonergodic microheterogeneity is an equilibrium property of every binary mixture with limited miscibility. The experimental status of this statement is discussed for eutectic and monotectic systems.

  16. On the ideality of binary mixtures of ionic liquids.

    PubMed

    Brüssel, Marc; Brehm, Martin; Pensado, Alfonso S; Malberg, Friedrich; Ramzan, Muhammad; Stark, Annegret; Kirchner, Barbara

    2012-10-14

    In this work, structural and dynamical properties of the binary mixture of 1-ethyl-3-methyl-imidazolium chloride and 1-ethyl-3-methyl-imidazolium thiocyanate are investigated from ab initio molecular dynamics simulations and compared to the pure ionic liquids. Furthermore, the binary mixture is simulated with two different densities to gain insight into how the selected density affects the different properties. In addition, a simple NMR experiment is carried out to investigate the changes of the chemical shifts of the hydrogen atoms due to the composition of the mixture.

  17. Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures

    SciTech Connect

    Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

    2009-09-27

    Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

  18. Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures

    SciTech Connect

    Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

    2011-02-14

    Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

  19. Dielectric Interactions in a Nematic Binary Mixture

    NASA Astrophysics Data System (ADS)

    Spears, Tom; Garg, Shila

    2002-03-01

    Phase transition investigations of mixtures of nematic liquid crystal materials with dissimilar dielectric anisotropies have shown the existence of an induced phase that is not exhibited by either of the systems. In this study, a phase diagram was developed for molar mixtures of nematic liquid crystals of 5CB and MBBA which for certain concentrations display an induced smectic B phase [1]. In order to understand the interaction of the two systems, dielectric permittivities ɛ_|| and ɛ_⊥ were measured for mixtures of various concentrations. In addition, the molecules were modeled and analyzed using a Silicon Graphics O2 workstation running the software Spartan 5.1. Different surfaces were calculated for a geometrically optimized molecule. Our investigations suggest strong interactions between the two systems. [1] A. Christine Rauch, Shila Garg and D. T. Jacobs, to appear in Journal of Chemical Physics (Feb. 2002). This research was supported by NSF DMR 9987850 and 9704579.

  20. Binary Mixtures of Particles with Different Diffusivities Demix.

    PubMed

    Weber, Simon N; Weber, Christoph A; Frey, Erwin

    2016-02-05

    The influence of size differences, shape, mass, and persistent motion on phase separation in binary mixtures has been intensively studied. Here we focus on the exclusive role of diffusivity differences in binary mixtures of equal-sized particles. We find an effective attraction between the less diffusive particles, which are essentially caged in the surrounding species with the higher diffusion constant. This effect leads to phase separation for systems above a critical size: A single close-packed cluster made up of the less diffusive species emerges. Experiments for testing our predictions are outlined.

  1. 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.

  2. Communication: Unusual dynamics of hybrid nanoparticles and their binary mixtures

    NASA Astrophysics Data System (ADS)

    Srivastava, S.; Chandran, Sivasurender; Kandar, A. K.; Sarika, C. K.; Basu, J. K.; Narayanan, S.; Sandy, A.

    2010-10-01

    We present the results on the evolution of microscopic dynamics of hybrid nanoparticles and their binary mixtures as a function of temperature and wave vector. We find unexpectedly a nonmonotonic dependence of the structural relaxation time of the nanoparticles as a function of the morphology. In binary mixtures of two of the largest nanoparticles studied, we observe re-entrant vitrification as a function of the volume fraction of the smaller nanoparticle, which is unusual for such high diameter ratio. Possible explanation for the observed behavior is provided.

  3. Evaporation of binary mixtures in microgravity

    NASA Technical Reports Server (NTRS)

    Girgis, Morris; Matta, Nabil; Kolli, Kiran; Brown, Leon; Chubb, Kevin

    1995-01-01

    The motivation of this research is to obtain a better understanding of phase-change heat transfer within single and binary liquid meniscii, both in 1-g and 0-g environments. During phase 1 and part of phase 2, in a glass test cell with an inclined heated plate, 1-6 experiments on pentane with additions of decane up to 3% were conducted to determine the optimum concentration that will exhibit the maximum heat transfer and stability. During phase 2 emphasis was given to explore fundamental research issues and to ultimately develop a reliable capillary pumped loop (CPL) device for low gravity. In related experimental work, it was found that thermocapillary stresses near the contract line could result in a degraded wettability which ultimately could explain the observed failure of CPL devices in zero-gravity environment. Therefore, the current experimental effort investigates the effect of adding binary constituents in improving the thermocapillary characteristics near the contact line within the loop configuration. Achievements during second phase include: (1) Further enhancement of Central State University's Microgravity Laboratory by adding or improving upon capabilities of photography, video imaging, fluid visualization, and general experimental testing capabilities; (2) Experimental results for the inclined plate cell; (3) Modeling effort with a detailed scaling analysis; (4) Additional testing with a tube loop configuration to extend experimental work by Dickens, et al.; (5) Fabrication of a capillary loop to be tested using binary fluid (pentane/decane). The device that has been recently completed will be set up horizontally so that the effect of gravity on the performance is negligible. Testing will cover a wide range of parameters such as decane/pentane concentration, heat input value, heat input location (below or above meniscus), and loop temperature.

  4. Evaporation of binary mixtures in microgravity

    NASA Technical Reports Server (NTRS)

    Girgis, Morris; Matta, Nabil; Kolli, Kiran; Brown, Leon; Chubb, Kevin

    1995-01-01

    The motivation of this research is to obtain a better understanding of phase-change heat transfer within single and binary liquid meniscii, both in 1-g and 0-g environments. During phase 1 and part of phase 2, in a glass test cell with an inclined heated plate, 1-6 experiments on pentane with additions of decane up to 3% were conducted to determine the optimum concentration that will exhibit the maximum heat transfer and stability. During phase 2 emphasis was given to explore fundamental research issues and to ultimately develop a reliable capillary pumped loop (CPL) device for low gravity. In related experimental work, it was found that thermocapillary stresses near the contract line could result in a degraded wettability which ultimately could explain the observed failure of CPL devices in zero-gravity environment. Therefore, the current experimental effort investigates the effect of adding binary constituents in improving the thermocapillary characteristics near the contact line within the loop configuration. Achievements during second phase include: (1) Further enhancement of Central State University's Microgravity Laboratory by adding or improving upon capabilities of photography, video imaging, fluid visualization, and general experimental testing capabilities; (2) Experimental results for the inclined plate cell; (3) Modeling effort with a detailed scaling analysis; (4) Additional testing with a tube loop configuration to extend experimental work by Dickens, et al.; (5) Fabrication of a capillary loop to be tested using binary fluid (pentane/decane). The device that has been recently completed will be set up horizontally so that the effect of gravity on the performance is negligible. Testing will cover a wide range of parameters such as decane/pentane concentration, heat input value, heat input location (below or above meniscus), and loop temperature.

  5. Isomorphic Viscosity Equation of State for Binary Fluid Mixtures.

    PubMed

    Behnejad, Hassan; Cheshmpak, Hashem; Jamali, Asma

    2015-01-01

    The thermodynamic behavior of the simple binary mixtures in the vicinity of critical line has a universal character and can be mapped from pure components using the isomorphism hypothesis. Consequently, based upon the principle of isomorphism, critical phenomena and similarity between P-ρ-T and T-η-(viscosity)-P relationships, the viscosity model has been developed adopting two cubic, Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR), equations of state (EsoS) for predicting the viscosity of the binary mixtures. This procedure has been applied to the methane-butane mixture and predicted its viscosity data. Reasonable agreement with the experimental data has been observed. In conclusion, we have shown that the isomorphism principle in conjunction with the mapped viscosity EoS suggests a reliable model for calculating the viscosity of mixture of hydrocarbons over a wide pressure range up to 35 MPa within the stated experimental errors.

  6. Cluster-cluster aggregation in binary mixtures

    NASA Astrophysics Data System (ADS)

    Alsunaidi, A.; Lach-Hab, M.; González, Agustín E.; Blaisten-Barojas, Estela

    2000-01-01

    The structure and aggregation kinetics of three-dimensional clusters composed of two different monomeric species at three concentrations are thoroughly investigated by means of extensive, large-scale computer simulations. The aggregating monomers have all the same size and occupy the cells of a cubic lattice. Two bonding schemes are considered: (a) the binary diffusion-limited cluster-cluster aggregation (BDLCA) in which only the monomers of different species stick together, and (b) the invading binary diffusion-limited cluster-cluster aggregation (IBDLCA) in which additionally monomers of one of the two species are allowed to bond. In the two schemes, the mixed aggregates display self-similarity with a fractal dimension df that depends on the relative molar fraction of the two species and on concentration. At a given concentration, when this molar fraction is small, df approaches a value close to the reaction-limited cluster-cluster aggregation of one-component systems, and when the molar fraction is 0.5, df becomes close to the value of the diffusion-limited cluster-cluster aggregation model. The crossover between these two regimes is due to a time-decreasing reaction probability between colliding particles, particularly at small molar fractions. Several dynamical quantities are studied as a function of time. The number of clusters and the weight-average cluster size display a power-law behavior only at small concentrations. The dynamical exponents are obtained for molar fractions above 0.3 but not at or below 0.2, indicating the presence of a critical transition between a gelling to a nongelling system. The cluster-size distribution function presents scaling for molar fractions larger than 0.2.

  7. Coal liquefaction process using pretreatment with a binary solvent mixture

    DOEpatents

    Miller, Robert N.

    1986-01-01

    An improved process for thermal solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a hydrogen donor solvent comprises pretreating the coal with a binary mixture of an aromatic hydrocarbon and an aliphatic alcohol at a temperature below 300.degree. C. before the hydroliquefaction step. This treatment generally increases both conversion of coal and yields of oil.

  8. Theory of asymmetric nonadditive binary hard-sphere mixtures.

    PubMed

    Roth, R; Evans, R; Louis, A A

    2001-11-01

    It is shown that the formal procedure of integrating out the degrees of freedom of the small spheres in a binary hard-sphere mixture works equally well for nonadditive as it does for additive mixtures. For highly asymmetric mixtures (small size ratios) the resulting effective Hamiltonian of the one-component fluid of big spheres, which consists of an infinite number of many-body interactions, should be accurately approximated by truncating after the term describing the effective pair interaction. Using a density functional treatment developed originally for additive hard-sphere mixtures the zero, one, and two-body contribution to the effective Hamiltonian are determined. It is demonstrated that even small degrees of positive or negative nonadditivity have significant effect on the shape of the depletion potential. The second virial coefficient B2, corresponding to the effective pair interaction between two big spheres, is found to be a sensitive measure of the effects of nonadditivity. The variation of B2 with the density of the small spheres shows significantly different behavior for additive, slightly positive and slightly negative nonadditive mixtures. Possible repercussions of these results for the phase behavior of binary hard-sphere mixtures are discussed and it is suggested that measurements of B2 might provide a means of determining the degree of nonadditivity in real colloidal mixtures.

  9. Composition measurements of binary mixture droplets by rainbow refractometry

    SciTech Connect

    Wilms, J.; Weigand, B

    2007-04-10

    So far, refractive index measurements by rainbow refractometry have been used to determine the temperature of single droplets and ensembles of droplets. Rainbow refractometry is, for the first time, to the best of our knowledge, applied to measure composition histories of evaporating, binary mixture droplets. An evaluation method is presented that makes use of Airy theory and the simultaneous size measurement by Mie scattering imaging. The method further includes an empirical correction function for a certain diameter and refractive index range. The measurement uncertainty was investigated by numerical simulations with Lorenz-Mie theory. For the experiments, an optical levitation setup was used allowing for long measurement periods. Temperature measurements of single-component droplets at different temperature levels are shown to demonstrate the accuracy of rainbow refractometry. Measurements of size and composition histories of binary mixture droplets are presented for two different mixtures. Experimental results show good agreement with numerical results using a rapid-mixing model.

  10. Composition measurements of binary mixture droplets by rainbow refractometry.

    PubMed

    Wilms, J; Weigand, B

    2007-04-10

    So far, refractive index measurements by rainbow refractometry have been used to determine the temperature of single droplets and ensembles of droplets. Rainbow refractometry is, for the first time, to the best of our knowledge, applied to measure composition histories of evaporating, binary mixture droplets. An evaluation method is presented that makes use of Airy theory and the simultaneous size measurement by Mie scattering imaging. The method further includes an empirical correction function for a certain diameter and refractive index range. The measurement uncertainty was investigated by numerical simulations with Lorenz-Mie theory. For the experiments, an optical levitation setup was used allowing for long measurement periods. Temperature measurements of single-component droplets at different temperature levels are shown to demonstrate the accuracy of rainbow refractometry. Measurements of size and composition histories of binary mixture droplets are presented for two different mixtures. Experimental results show good agreement with numerical results using a rapid-mixing model.

  11. Coarsening in binary solid-liquid mixtures

    NASA Technical Reports Server (NTRS)

    Voorhees, P. W.

    1990-01-01

    A theory of Ostwald ripening has been developed for a solid-liquid mixture cosisting of a low volume fraction array of spherical solid particles in a liquid wherein the coarsening process proceeds via the transport of both heat and mass. It is found that the simultaneous transport of heat and mass during ripening does not alter the exponents of the temporal power laws governing the ripening process from their classical values but does alter the amplitudes of these power laws. The growth rate of the cube of the average particle radius, the rate constant, is found to depend both on the alloy solute concentration and the ratio of the thermal to solutal diffusivities. In most metallic systems, a large decrease in the rate constant can be expected with small additions of solute to a pure metal. Possible extensions of this theory to the analogous problem of ripening in isothermal ternary alloys are also discussed.

  12. Effective Potential Theory for Diffusion in Binary Ionic Mixtures

    NASA Astrophysics Data System (ADS)

    Shaffer, Nathaniel R.; Baalrud, Scott D.; Daligault, Jerome

    2016-10-01

    We present theoretical predictions of diffusion coefficients for classical binary ionic mixtures spanning weak to strong coupling. Strongly coupled, classical ionic mixtures are realized in non-neutral plasmas, and they serve as a useful reference system for ultracold plasmas and warm dense matter. We model many-body correlation effects on transport by treating binary interactions via the potential of mean force and by treating the Coulomb hole around each ion with an effective exclusion radius. This approach is known to agree closely with molecular dynamics results for the transport properties of single-component plasmas - including warm dense matter - up to the onset of liquid-like correlations, and we find a comparable range of agreement for the interdiffusion coefficient of binary ionic mixtures. We also present the self-diffusion coefficients of the two ion species in a mixture, in light of recent measurements in ultracold neutral plasmas. An outlook for applying the theory to electron-ion transport in the strong coupling regime is also considered. The authors gratefully acknowledge support from NSF Grant PHY-1453736.

  13. Thermodiffusion of polycyclic aromatic hydrocarbons in binary mixtures

    NASA Astrophysics Data System (ADS)

    Hashmi, Sara M.; Senthilnathan, Sid; Firoozabadi, Abbas

    2016-11-01

    Thermodiffusion in liquid mixtures may explain some counter-intuitive but naturally occurring phenomena such as hydrocarbon reservoirs with heavier component(s) stratified on top of lighter ones. However, beyond benchmark systems, systematic measurements of thermodiffusion in binary organic mixtures are lacking. We use an optical beam deflection apparatus to simultaneously probe Fickian and thermal diffusion in binary solution mixtures of polycyclic aromatic hydrocarbons dissolved in alkanes, and measure both Fickian diffusion D and the Soret coefficient ST, and then obtain the thermodiffusion coefficient DT. In a series of nine binary mixtures, we vary both the size of the aromatic compound from two to four rings, as well as the length of the alkane chain from 6 to 16 carbons. To probe the effect of increasing ring size, we include a 6-ringed aromatic compound, coronene, and toluene as a solvent, due to the insolubility of coronene in alkanes. Our results suggest that Fickian diffusion increases with the inverse of solvent viscosity and also with decreasing molecular weight of the solute. While both of these trends match our intuition, the behavior of ST and DT is more complicated. We find that ST and DT increase with the solute molecular weight when the solvent is held fixed and that the impact of solute ring size is higher in shorter chain alkane solvents.

  14. DSMC simulation of Rayleigh-Brillouin scattering in binary mixtures

    NASA Astrophysics Data System (ADS)

    Bruno, Domenico; Frezzotti, Aldo; Ghiroldi, Gian Pietro

    2016-11-01

    Rayleigh-Brillouin scattering spectra (RBS) in dilute gas mixtures have been simulated by the Direct Simulation Monte Carlo method (DSMC). Different noble gas binary mixtures have been considered and the spectra have been simulated adopting the hard sphere collision model. It is suggested that DSMC simulations can be used in the interpretation of light scattering experiments in place of approximate kinetic models. Actually, the former have a firmer physical ground and can be readily extended to treat gas mixtures of arbitrary complexity. The results obtained confirm the capability of DSMC to predict experimental spectra and clears the way towards the simulation of polyatomic gas mixtures of interest for actual application (notably, air) where tractable kinetic model equations are still lacking.

  15. Crystallization of binary ionic mixtures in dense stellar plasmas

    NASA Astrophysics Data System (ADS)

    Segretain, L.; Chabrier, G.

    1993-04-01

    The crystallization diagrams of arbitrary dense binary ionic mixtures are examined within the framework of the density-functional theory of freezing. The behaviour of the phase diagram is shown to depend strongly on the charge ratio in the mixture. As the charge ratio Z1/Z2 is lowered, the phase diagram evolves from a spindle shape into an azeotropic phase diagram and finally into a eutectic phase diagram. This has import ant consequences on the crystallization of trace elements in White Dwarfs, and on the subsequent gravitational energy release, leading to a substantial modification of the cooling history of these stars.

  16. Bose-Einstein condensation in binary mixture of Bose gases

    SciTech Connect

    Tran Huu Phat; Le Viet Hoa; Nguyen Tuan Anh Nguyen Van Long

    2009-10-15

    The Bose-Einstein condensation (BEC) in a binary mixture of Bose gases is studied by means of the Cornwall-Jackiw-Tomboulis (CJT) effective action approach. The equations of state (EoS) and various scenarios of phase transitions of the system are considered in detail, in particular, the numerical computations are carried out for symmetry restoration (SR), symmetry nonrestoration (SNR) and inverse symmetry breaking (ISB) for getting an insight into their physical nature. It is shown that due to the cross interaction between distinct components of mixture there occur two interesting phenomena: the high temperature BEC and the inverse BEC, which could be tested in experiments.

  17. Theory of amorphous packings of binary mixtures of hard spheres.

    PubMed

    Biazzo, Indaco; Caltagirone, Francesco; Parisi, Giorgio; Zamponi, Francesco

    2009-05-15

    We extend our theory of amorphous packings of hard spheres to binary mixtures and more generally to multicomponent systems. The theory is based on the assumption that amorphous packings produced by typical experimental or numerical protocols can be identified with the infinite pressure limit of long-lived metastable glassy states. We test this assumption against numerical and experimental data and show that the theory correctly reproduces the variation with mixture composition of structural observables, such as the total packing fraction and the partial coordination numbers.

  18. Shear viscosity of binary mixtures: The Gay-Berne potential

    NASA Astrophysics Data System (ADS)

    Khordad, R.

    2012-05-01

    The Gay-Berne (GB) potential model is an interesting and useful model to study the real systems. Using the potential model, we intend to examine the thermodynamical properties of some anisotropic binary mixtures in two different phases, liquid and gas. For this purpose, we apply the integral equation method and solve numerically the Percus-Yevick (PY) integral equation. Then, we obtain the expansion coefficients of correlation functions to calculate the thermodynamical properties. Finally, we compare our results with the available experimental data [e.g., HFC-125 + propane, R-125/143a, methanol + toluene, benzene + methanol, cyclohexane + ethanol, benzene + ethanol, carbon tetrachloride + ethyl acetate, and methanol + ethanol]. The results show that the GB potential model is capable for predicting the thermodynamical properties of binary mixtures with acceptable accuracy.

  19. Determination of metformin hydrochloride and glyburide in an antihyperglycemic binary mixture using high-performance liquid chromatographic-UV and spectrometric methods.

    PubMed

    Salem, Hesham

    2010-01-01

    Three methods were developed for simultaneous determination of metformin hydrochloride and glyburide in an antihyperglycemic binary mixture without previous separation. In the first method, a reversed-phase HPLC column with acetonitrile-water (60 + 40, v/v) mobile phase at 0.9 mL/min flow rate was used to separate both compounds, with UV detection at 254 nm. Linearity was obtained in the concentration range of 0.06--0.24 microg/mL for glyburide and 1.5-6.0 microg/mL for metformin hydrochloride. The second method depended on first- and second-derivative UV spectrometry with zero-crossing measurements. The first-derivative amplitude at 261 nm was selected for the assay of glyburide, and the second-derivative amplitude at 235 nm was selected for the assay of metformin hydrochloride. The third method depended on measuring the first derivative of the ratio-spectra at 241 nm for glyburide and 227 nm for metformin hydrochloride. For the second and third methods, Beer's law was obeyed in the range of 10-55 microg/mL for glyburide and 20-200 microg/mL for metformin. The proposed methods were extensively validated and applied for the analysis of some pharmaceutical formulations containing binary mixtures of the mentioned drugs.

  20. Smoothed particle hydrodynamics model for phase separating fluid mixtures. II. Diffusion in a binary mixture.

    PubMed

    Thieulot, Cedric; Janssen, L P B M; Español, Pep

    2005-07-01

    A previously formulated smoothed particle hydrodynamics model for a phase separating mixture is tested for the case when viscous processes are negligible and only mass and energy diffusive processes take place. We restrict ourselves to the case of a binary mixture that can exhibit liquid-liquid phase separation. The thermodynamic consistency of the model is assessed and the potential of the model to study complex pattern formation in the presence of various thermal boundaries is illustrated.

  1. Viscosity and mutual diffusion in strongly asymmetric binary ionic mixtures

    SciTech Connect

    Bastea, Sorin

    2005-05-01

    We present molecular dynamics simulation results for the viscosity and mutual diffusion constant of a strongly asymmetric binary ionic mixture. We compare the results with available theoretical models previously tested for much smaller asymmetries. For the case of viscosity we propose a predictive framework based on the linear mixing rule, while for mutual diffusion we discuss some consistency problems of widely used Boltzmann-equation-based models.

  2. Coal liquefaction process using pretreatment with a binary solvent mixture

    DOEpatents

    Miller, R.N.

    1986-10-14

    An improved process for thermal solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a hydrogen donor solvent comprises pretreating the coal with a binary mixture of an aromatic hydrocarbon and an aliphatic alcohol at a temperature below 300 C before the hydroliquefaction step. This treatment generally increases both conversion of coal and yields of oil. 1 fig.

  3. Investigation of synergism in binary mixtures of sweeteners.

    PubMed

    Schiffman, S S; Booth, B J; Carr, B T; Losee, M L; Sattely-Miller, E A; Graham, B G

    1995-01-01

    The purpose of the present study was to determine the presence and degree of synergism among all binary mixtures of 14 sweeteners varying in chemical structure. A trained panel evaluated binary combinations of the following sweeteners: three sugars (fructose, glucose, sucrose), two polyhydric alcohols (mannitol, sorbitol), two diterpenoid glycosides (rebaudioside-A, stevioside), two dipeptide derivatives (alitame, aspartame), one sulfamate (sodium cyclamate), one protein (thaumatin), two N-sulfonyl amides (acesulfame-K, sodium saccharin), and one dihydrochalcone (neohesperidin dihydrochalcone). Each sweetener was tested at three concentrations that were isosweet with 3%, 5%, and 7% sucrose. Two methods of analysis were performed to determine synergistic effects. In Method I, an ANOVA was performed for each intensity level to determine if the mean sweetness intensity ratings of each binary mixture were equal to nominal sweetness (i.e., additivity) or not equal to nominal sweetness (i.e., synergism or suppression). In Method II, an additional ANOVA was performed to determine if the sweetness intensity ratings of any given mixture were equal to or greater than the average of the sweetness ratings of the two pure components in that blend.

  4. Effects of lubricants on binary direct compression mixtures.

    PubMed

    Uğurlu, T; Halaçoğlu, M D; Türkoğlu, M

    2010-04-01

    The objective of this study was to investigate the effects of conventional lubricants including a new candidate lubricant on binary direct compression mixtures. Magnesium stearate (MGST), stearic acid (STAC), glyceryl behenate (COMP) and hexagonal boron nitride (HBN) were tested. The binary mixtures were 1:1 combinations of spray dried lactose (FlowLac 100), dicalcium phosphate dihydrate (Emcompress), and modified starch (Starch 1500) with microcrystalline cellulose (Avicel PH 102). Tablets were manufactured on a single-station instrumented tablet press with and without lubricants. In the case of unlubricated granules, the modified starch-microcrystalline cellulose mixture provided the highest percent compressibility value at 8.25%, spray dried lactose-microcrystalline cellulose mixture was 7.33%, and the dialcium phosphate dihydrate-microcrystalline cellulose mixture was 5.79%. Their corresponding tablet crushing strength values were: 104 N, 117 N, and 61 N, respectively. The lubricant concentrations studied were 0.5, 1, 2, and 4%. Effects of lubricant type and lubricant concentration on crushing strength were analyzed using a factorial ANOVA model. It was found that the Avicel PH 102-Starch 1500 mixture showed the highest lubricant sensitivity (110 N vs. 9 N), the least affected formulation was FlowLac-Avicel PH 102 mixture (118 N vs. 62 N). The crushing strength vs. concentration curve for MGST showed a typical biphasic profile, a fast drop up to 1% and a slower decline between 1 and 4%. The STAC, COMP, and HBN for all formulations showed a shallow linear decline of tablet crushing strength with increasing lubricant concentration. The HBN was as effective as MGST as a lubricant, and did not show a significant negative effect on the crushing strength of the tablets. The COMP and STAC also did not interfere with the crushing strength, however, they were not as effective lubricants as MGST or HBN.

  5. Viscosity minima in binary mixtures of ionic liquids + molecular solvents.

    PubMed

    Tariq, M; Shimizu, K; Esperança, J M S S; Canongia Lopes, J N; Rebelo, L P N

    2015-05-28

    The viscosity (η) of four binary mixtures (ionic liquids plus molecular solvents, ILs+MSs) was measured in the 283.15 < T/K < 363.15 temperature range. Different IL/MS combinations were selected in such a way that the corresponding η(T) functions exhibit crossover temperatures at which both pure components present identical viscosity values. Consequently, most of the obtained mixture isotherms, η(x), exhibit clear viscosity minima in the studied T-x range. The results are interpreted using auxiliary molecular dynamics (MD) simulation data in order to correlate the observed η(T,x) trends with the interactions in each mixture, including the balance between electrostatic forces and hydrogen bonding.

  6. Molecular dynamics simulation of binary mixtures of molten alkali carbonates

    NASA Astrophysics Data System (ADS)

    Tissen, J. T. W. M.; Janssen, G. J. M.; van der Eerden, P.

    Molecular dynamics simulations have been performed on three binary eutectic mixtures: Li/NaCO3 (53-47 mol%), Li/KCO3 (62-38 mol%) and KCO3 (43-57 mol%) at 1200 K. The short-range order in the mixtures differs in many respects from the short-range order found in the pure components. The Li+ ions are coordinated by a smaller number of oxygen atoms, the Na+ and K+ ions by a larger number. The Li+ ions become trapped in their first coordination shell, leaving relatively more space for the larger atoms. This feature is the cause of the often-observed non-additivity of the dynamic properties of these mixtures, such as the Chemla effect in Li/KCO3, the large negative deviations from linear additivity for the electrical conductivity, as well as the dependence of the self-diffusion coefficient of the cations on the Li2CO3 content.

  7. Photophysical study of Zn phthalocyanine in binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Staicu, A.; Pascu, A.; Boni, M.; Pascu, M. L.; Enescu, M.

    2013-07-01

    Photophysical properties of phthalocyanines are important in photodynamic therapy, where these compounds are proposed as photosensitizing agents. We report here some significant solvent effects on the photophysical properties of Zn phthalocyanine (ZnPc) observed in binary solvent mixture dimethyl sulfoxide/water at several ratios of cosolvents. The absorbance of ZnPc at the maximum of Q band has a sharp drop in intensity for a water mass percent in the solvent mixture larger than 40%. The same characteristic shows also the quantum yield of fluorescence. A particular result is the increase of singlet oxygen lifetime for water percentage raise up to 20% in the solvent mixture. The effects are discussed in connection with the particular solvent microenvironment, involving DMSO/water clusters formation and the strong interaction between the solute and the solvent.

  8. Simple binary mixtures of hydrogen and ammonia under extreme pressures

    NASA Astrophysics Data System (ADS)

    Borstad, Gustav; Yoo, Choong-Shik

    2013-03-01

    Binary mixtures under pressure are of interest as fundamental systems in physics and chemistry as they allow the effects of the environment on the behavior of different chemical compounds to be examined. Furthermore, mixtures of simple molecular systems are of interest for applications in fuel cells and also to planetary science due to their presence in the interiors of the giant gas planets. In this presentation, Raman data on the ammonia and hydrogen system under pressure will be presented, and the extent and nature of the interactions in this mixture will be discussed. The work has been supported by NSF (DMR-0854618 and DMR-1203834); GB was also supported by the ISP scholarship at WSU.

  9. Thermodynamic instabilities of a binary mixture of sticky hard spheres.

    PubMed

    Fantoni, Riccardo; Gazzillo, Domenico; Giacometti, Achille

    2005-07-01

    The thermodynamic instabilities of a binary mixture of sticky hard spheres (SHS) in the modified mean spherical approximation (mMSA) and the Percus-Yevick (PY) approximation are investigated using an approach devised by Chen and Forstmann [corrected] [J. Chem. Phys. [corrected] 97, 3696 (1992)]. This scheme hinges on a diagonalization of the matrix of second functional derivatives of the grand canonical potential with respect to the particle density fluctuations. The zeroes of the smallest eigenvalue and the direction of the relative eigenvector characterize the instability uniquely. We explicitly compute three different classes of examples. For a symmetrical binary mixture, analytical calculations, both for mMSA and for PY, predict that when the strength of adhesiveness between like particles is smaller than the one between unlike particles, only a pure condensation spinodal exists; in the opposite regime, a pure demixing spinodal appears at high densities. We then compare the mMSA and PY results for a mixture where like particles interact as hard spheres (HS) and unlike particles as SHS, and for a mixture of HS in a SHS fluid. In these cases, even though the mMSA and PY spinodals are quantitatively and qualitatively very different from each other, we prove that they have the same kind of instabilities. Finally, we study the mMSA solution for five different mixtures obtained by setting the stickiness parameters equal to five different functions of the hard sphere diameters. We find that four of the five mixtures exhibit very different type of instabilities. Our results are expected to provide a further step toward a more thoughtful application of SHS models to colloidal fluids.

  10. Rheology of binary granular mixtures in the dense flow regime

    NASA Astrophysics Data System (ADS)

    Tripathi, Anurag; Khakhar, D. V.

    2011-11-01

    We study the rheology of granular mixtures in a steady, fully developed, gravity-driven flow on an inclined plane, by means of discrete element method (DEM) simulations. Results are presented for a single component system and binary mixtures with particles of different size and density. Inclination angles, composition, size ratios and density ratios are varied to obtain different segregated configurations at equilibrium. Steady state profiles of the mean velocity, volume fractions, shear stress, shear rate, inertial number and apparent viscosity across the depth of the flowing layer are reported for the different cases. The viscosity varies with height and is found to depend on the local bulk density and composition, which, in turn, depend on the size ratio, the mass ratio and the degree of segregation. For a single component system, a viscoplastic rheological model [P. Jop et al., Nature 441, 727 (2006)] describes the data quite well. We propose a modification of the model for the case of mixtures. The mixture model predicts the viscosity for both well-mixed and segregated granular mixtures differing in size, density or both, using the same model parameters as obtained for the single component system. The predictions of a model for the volume fraction of the mixtures also agree well with simulation results.

  11. Molecular dynamics simulation study of binary fullerene mixtures

    NASA Astrophysics Data System (ADS)

    Ruberto, R.; Abramo, M. C.; Caccamo, C.

    2004-10-01

    We report constant-pressure molecular dynamics (MD) simulations of binary C60/Cn fullerene-mixtures ( n=70 , 76, 84, 96) modeled in terms of a spherically symmetric two-body potential. By starting from a liquid configuration of the system, we cool mixtures down to freezing and beyond, until room temperature is reached, in order to verify the formation of solid solutions, namely, of configurations characterized by a unique crystalline lattice whose sites are randomly occupied by the two component fullerene species. We first explore the entire concentration range of the C60x/C70(1-x)(0mixture and find fairly good agreement with experimental data, exhibiting partial reciprocal solubility of the two components into each other with an immiscibility gap at intermediate compositions. In fact, the system we simulate forms substitutional solid solutions over a wide range of concentrations except for 0.3⩽x⩽0.5 ; over such an interval, it turns out that the initially liquid mixture can be supercooled down to relatively low temperatures, until eventually a glassy phase is formed. The study is then extended to fullerene mixtures of molecular diameter ratio α=σC60/σCn smaller than in C60/C70 (where α=0.93 ), as is the case for C60/C76 (α=0.89) , C60/C84(α=0.85) and C60/C96 (α=0.79) . The effect of the size mismatch between the two species is dramatic: The solid immiscibility region rapidly expands even upon a tiny reduction of α , with formation of an amorphous phase at sufficiently low temperature, as found for the C60/C70 mixture. For the smallest α(C60/C96) cocrystallization of the two components turns out to be forbidden over the whole concentration axis. A mapping of the MD evidences of the fullerene mixtures’ phase behavior onto the phase diagram of binary hard-sphere mixtures (determined by other authors) turns out to be worthwhile and enlightnening. In particular, size ratio effects and the onset of glassy phases emerge in qualitative good agreement

  12. On the phase behavior of binary mixtures of nanoparticles.

    PubMed

    Ben-Simon, Avi; Eshet, Hagai; Rabani, Eran

    2013-02-26

    The assembly of mixtures of nanoparticles with different properties into a binary nanoparticle superlattice (BNSL) provides a route to fabricate novel classes of materials with properties emerging from the choice of the building blocks. The common theoretical approach based on the hard-spheres model predicts crystallization of only a few metastable binary superstructures (NaCl, AlB₂ or the AB₁₃). Recently [Shevchenko, E. V.; Talapin, D. V.; O'Brien, S.; Murray, C. B. Nature 2006; 439, 55.)], it has been demonstrated that with the use of a combination of semiconducting, metallic, and magnetic nanoparticles, a variety of novel BNSL structures were formed, where at least 10 were low density structures that have not been previously reported. While some of the structures can be explained by the addition of electrostatic interactions, it is clear that at the nanometer scale one needs to consider other influences, such as van der Waals forces, steric effects, etc. Motivated by those experiments, we study, using Monte Carlo simulations, the phase behavior of binary mixtures of nanoparticles interacting via a combination of hard-core electrostatics and van der Waals forces. We include a tuning parameter that can be used to balance between electrostatic and dispersion interactions and study the phase behavior as a function of the different charges and size ratios of the nanoparticles. The results indicate that at the nanoscale, both electrostatic and dispersion interactions are necessary to explain the experimental observed BNSL structures.

  13. Crystallization kinetics of colloidal binary mixtures with depletion attraction.

    PubMed

    Kozina, Anna; Díaz-Leyva, Pedro; Palberg, Thomas; Bartsch, Eckhard

    2014-12-21

    In this work the crystallization kinetics of colloidal binary mixtures with attractive interaction potential (Asakura-Oosawa) has been addressed. Parameters such as fraction of crystals, linear crystal dimension and crystal packing have been quantified in order to understand how the crystal formation is driven in terms of the depth of the attractive potential and the composition of the binary mixture (described by the number ratio). It was found that inside the eutectic triangle, crystallization is mainly governed by nucleation and the crystal packing is close to the close-packing of hard spheres. Moving out from the eutectic triangle towards small component results in the crystallization of small spheres. Enrichment of the eutectic mixture with large component results in the crystallization of both large and small spheres, however, the kinetics are completely different from those of the eutectic composition. Crosslinked polystyrene microgels with nearly hard sphere interactions were used as model systems. Attraction was introduced by addition of linear polystyrene. The time evolution of crystallization has been followed by static light scattering.

  14. Marangoni Effects in the Boiling of Binary Fluid Mixtures

    NASA Technical Reports Server (NTRS)

    Ahmed, Sayeed; Carey, Van P.; Motil, Brian

    1996-01-01

    Results of very recent experimental studies indicate that during nucleate boiling in some binary mixture, Marangoni effects augment the gravity driven flow of liquid towards the heated surface. With gravity present, it is impossible to separate the two effects. The reduced gravity environment gives an unique opportunity to explore th role of Marangoni effects on the boiling mechanisms free of gravitational body forces that obscure the role of such effects. However, recent experimental results suggest that under reduced gravity conditions, Marangoni effects is the dominant mechanism of vapor-liquid exchange at the surface for some binary mixture. To further explore such effects, experiments have been conducted with water/2-propanol mixtures at three different concentrations under normal gravity with different orientations of the heater surface and under reduce gravity aboard the DC-9 aircraft at NASA Lewis Research Center. The system pressure was sub atmospheric (approx. 8 kP at 1g(n)) and the bulk liquid temperature varied from low subcooling to near saturation. The molar concentrations of 2-propanol tested were 0.015, 0.025, and 0.1. Boiling curves were obtained both for high gravity (approx. 2g(n)) and reduce gravity (approx. 0.01g(n)). For each concentration of 2-propanol, the critical heat flux has been determined in the flight experiments only for reduced gravity conditions. Comparison of boiling curves and CHF obtained under l-g(n) an reduced gravity indicates that boiling mechanism in this mixtures is nearly independent of gravity. The results also indicate that the Marangoni mechanism is strong enough in these mixtures to sustain the boiling under reduced gravity conditions.

  15. Solubility of pyrene in binary alkane + 1-octanol solvent mixtures

    SciTech Connect

    Zvaigzne, A.I.; Acree, W.E. Jr.

    1995-09-01

    Solid-liquid equilibrium data of organic nonelectrolyte systems are becoming increasingly important in the petroleum industry, particularly in light of present trends toward heavier feedstocks and known carcinogenicity/mutagenicity of many of the larger polycyclic aromatic compounds. Experimental solubilities are reported for pyrene dissolved in seven binary mixtures containing 1-octanol with hexane, heptane, octane, cyclohexane, methylcyclohexane, 2,2,4-trimethylpentane, and (1,1-dimethylethyl)cyclohexane at 26 C. Results of these measurements are used to test two mathematical representations based upon the combined nearly ideal binary solvent (NIBS)/Redlich-Kister equation and modified Wilson model. For the system studied, the three-parameter combined NIBS/Redlich-Kister equation was found to provide the better mathematical representation, with deviations between experimental and back-calculated values being on the order of {+-}1.5% or lees. Slightly larger deviations were noted in the case of the two-parameter modified Wilson equation.

  16. Phase behavior of a binary fluid mixture of quadrupolar molecules

    NASA Astrophysics Data System (ADS)

    Toda, Masatoshi; Kajimoto, Shinji; Toyouchi, Shuichi; Kawakatsu, Toshihiro; Akama, Yohji; Kotani, Motoko; Fukumura, Hiroshi

    2016-11-01

    We propose a model molecule to investigate microscopic properties of a binary mixture with a closed-loop coexistence region. The molecule is comprised of a Lennard-Jones particle and a uniaxial quadrupole. Gibbs ensemble Monte Carlo simulations demonstrate that the high-density binary fluid of the molecules with the quadrupoles of the same magnitude but of the opposite signs can show closed-loop immiscibility. We find that an increase in the magnitude of the quadrupoles causes a shrinkage of the coexistence region. Molecular dynamics simulations also reveal that aggregates with two types of molecules arranged alternatively are formed in the stable one-phase region both above and below the coexistence region. String structures are dominant below the lower critical solution temperature, while branched aggregates are observed above the upper critical solution temperature. We conclude that the anisotropic interaction between the quadrupoles of the opposite signs plays a crucial role in controlling these properties of the phase behavior.

  17. Enhanced Crystal Growth in Binary Lennard-Jones Mixtures

    NASA Astrophysics Data System (ADS)

    Radu, M.; Kremer, K.

    2017-02-01

    We study the crystal growth in binary Lennard-Jones mixtures by molecular dynamics simulations. Growth dynamics, the structure of the liquid-solid interfaces as well as droplet incorporation into the crystal vary with solution properties. For demixed systems we observe a strongly enhanced crystal growth at the cost of enclosed impurities. Furthermore, we find different interface morphologies depending on solubility. We relate our observations to growth mechanisms based on the Gibbs-Thomson effect as well as to predictions of the Kardar-Parisi-Zhang theory in 2 +1 dimensions.

  18. Soret motion in non-ionic binary molecular mixtures.

    PubMed

    Leroyer, Yves; Würger, Alois

    2011-08-07

    We study the Soret coefficient of binary molecular mixtures with dispersion forces. Relying on standard transport theory for liquids, we derive explicit expressions for the thermophoretic mobility and the Soret coefficient. Their sign depends on composition, the size ratio of the two species, and the ratio of Hamaker constants. Our results account for several features observed in experiment, such as a linear variation with the composition; they confirm the general rule that small molecules migrate to the warm, and large ones to the cold.

  19. Effective potential theory for diffusion in binary ionic mixtures.

    PubMed

    Shaffer, Nathaniel R; Baalrud, Scott D; Daligault, Jérôme

    2017-01-01

    Self-diffusion and interdiffusion coefficients of binary ionic mixtures are evaluated using the effective potential theory (EPT), and the predictions are compared with the results of molecular dynamics simulations. We find that EPT agrees with molecular dynamics from weak coupling well into the strong-coupling regime, which is a similar range of coupling strengths as previously observed in comparisons with the one-component plasma. Within this range, typical relative errors of approximately 20% and worst-case relative errors of approximately 40% are observed. We also examine the Darken model, which approximates the interdiffusion coefficients based on the self-diffusion coefficients.

  20. Effective potential theory for diffusion in binary ionic mixtures

    NASA Astrophysics Data System (ADS)

    Shaffer, Nathaniel R.; Baalrud, Scott D.; Daligault, Jérôme

    2017-01-01

    Self-diffusion and interdiffusion coefficients of binary ionic mixtures are evaluated using the effective potential theory (EPT), and the predictions are compared with the results of molecular dynamics simulations. We find that EPT agrees with molecular dynamics from weak coupling well into the strong-coupling regime, which is a similar range of coupling strengths as previously observed in comparisons with the one-component plasma. Within this range, typical relative errors of approximately 20% and worst-case relative errors of approximately 40% are observed. We also examine the Darken model, which approximates the interdiffusion coefficients based on the self-diffusion coefficients.

  1. Bubble nucleation in a Lennard-Jones binary liquid mixture

    NASA Astrophysics Data System (ADS)

    Baidakov, Vladimir G.; Protsenko, Sergey P.; Bryukhanov, Vasiliy M.

    2016-10-01

    We report a molecular dynamics (MD) study of homogeneous bubble nucleation in a stretched Lennard-Jones binary mixture at a temperature close to the solvent triple point. The pressure of the limiting stretching pn corresponding to a fixed value of the nucleation rate has been determined. The values of pn achieved in MD simulation are lower than those calculated from classical nucleation theory (CNT). The discrepancy between the data of MD simulation and CNT may be connected with the neglect in the latter of the size dependence of the surface tension of critical bubbles.

  2. Enhanced Crystal Growth in Binary Lennard-Jones Mixtures.

    PubMed

    Radu, M; Kremer, K

    2017-02-03

    We study the crystal growth in binary Lennard-Jones mixtures by molecular dynamics simulations. Growth dynamics, the structure of the liquid-solid interfaces as well as droplet incorporation into the crystal vary with solution properties. For demixed systems we observe a strongly enhanced crystal growth at the cost of enclosed impurities. Furthermore, we find different interface morphologies depending on solubility. We relate our observations to growth mechanisms based on the Gibbs-Thomson effect as well as to predictions of the Kardar-Parisi-Zhang theory in 2+1 dimensions.

  3. Mechanisms in size segregation of binary granular mixtures

    NASA Astrophysics Data System (ADS)

    Ulrich, Stephan; Kreft, Jennifer; Schröter, Matthias; Swift, Jack; Swinney, Harry

    2006-03-01

    Shaking of a mixture of large and small particles can lead to segregation. One distinguishes between the Brazil-nut effect (large particles go to the top) and its opposite, the reverse Brazil-nut effect. In this talk, experiments of vertically shaken binary mixtures are presented. Using image analysis, the number of large particles visible at the top and bottom of the granulate are counted to determine the state of segregation. By complementing these results with molecular dynamics simulations, we are able to identify different segregation mechanisms discussed in recent theoretical approaches: a geometrical mechanism called void filling, transport of particles in sidewall-driven convection rolls, and thermal diffusion, a mechanism predicted by kinetic theory.

  4. Low velocity ion stopping in binary ionic mixtures

    SciTech Connect

    Tashev, Bekbolat; Baimbetov, Fazylkhan; Deutsch, Claude; Fromy, Patrice

    2008-10-15

    Attention is focused on the low ion velocity stopping mechanisms in multicomponent and dense target plasmas built of quasiclassical electron fluids neutralizing binary ionic mixtures, such as, deuterium-tritium of current fusion interest, proton-heliumlike iron in the solar interior or proton-helium ions considered in planetology, as well as other mixtures of fiducial concern in the heavy ion beam production of warm dense matter at Bragg peak conditions. The target plasma is taken in a multicomponent dielectric formulation a la Fried-Conte. The occurrence of projectile ion velocities (so-called critical) for which target electron slowing down equals that of given target ion components is also considered. The corresponding multiquadrature computations, albeit rather heavy, can be monitored analytical through a very compact code operating a PC cluster. Slowing down results are systematically scanned with respect to target temperature and electron density, as well as ion composition.

  5. Salt-induced microheterogeneities in binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Bier, Markus; Mars, Julian; Li, Hailong; Mezger, Markus

    2017-08-01

    The salt-induced microheterogeneity (MH) formation in binary liquid mixtures is studied by small-angle x-ray scattering (SAXS) and liquid state theory. Previous experiments have shown that this phenomenon occurs for antagonistic salts, whose cations and anions prefer different components of the solvent mixture. However, so far the precise mechanism leading to the characteristic length scale of MHs has remained unclear. Here, it is shown that MHs can be generated by the competition of short-ranged interactions and long-ranged monopole-dipole interactions. The experimental SAXS patterns can be reproduced quantitatively by fitting to the derived correlation functions without assuming any specific model. The dependency of the MH structure with respect to ionic strength and temperature is analyzed. Close to the demixing phase transition, critical-like behavior occurs with respect to the spinodal line in the phase diagram.

  6. Probing glassy states in binary mixtures of soft interpenetrable colloids.

    PubMed

    Stiakakis, E; Erwin, B M; Vlassopoulos, D; Cloitre, M; Munam, A; Gauthier, M; Iatrou, H; Hadjichristidis, N

    2011-06-15

    We present experimental evidence confirming the recently established rich dynamic state diagram of asymmetric binary mixtures of soft colloidal spheres. These mixtures consist of glassy suspensions of large star polymers to which different small stars are added at varying concentrations. Using rheology and dynamic light scattering measurements along with a simple phenomenological analysis, we show the existence of re-entrance and multiple glassy states, which exhibit distinct features. Cooperative diffusion, as a probe for star arm interpenetration, is proven to be sensitive to the formation of the liquid pockets which signal the melting of the large-star-glass upon addition of small stars. These results provide ample opportunities for tailoring the properties of soft colloidal glasses.

  7. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, Scott R.; Christophorou, Loucas G.

    1990-01-01

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

  8. Distillation of binary mixtures with capillary porous plates

    SciTech Connect

    Abu Al-Rub, F.A.; Akili, J.; Datta, R.

    1998-07-01

    Distillation of liquid mixtures using capillary porous plates is a new process which depends upon the use of the intermolecular interactions between solids and liquids to alter the normal vapor-liquid equilibrium of a given mixture. Distillation of different binary mixtures, namely ethanol-water, ethanol-benzene, and acetone-ethanol systems, of different compositions was experimentally studied in a continuous distillation column equipped with four, five, or six porous sintered stainless steel fractionating plates of 13.5 {micro}m pore diameter as well as six normal sieve plates. The results showed that the main factors affecting the separation efficiency in a given porous plate are the polarization of the pure liquids and the polarization difference between the mixture components. For the ethanol-water system, the results showed that while no separation was achieved in a distillation column with conventional stages, the zeotropic point of this system was broken in the distillation column with porous plates. A distillate of about 94 mol% ethanol was obtained for a feed of the zeotropic composition, i.e., 89.7 mol% ethanol. For the ethanol-benzene system, the azeotropic point was shifted from 40 mol% ethanol to about 30 mol% ethanol. For the acetone-ethanol system, there was no significant difference between the results obtained with normal stages and those with the porous plates. These results are in agreement with the developed theory.

  9. Stability and hydrodynamics of conical spouted beds with binary mixtures

    SciTech Connect

    Olazar, M.; San Jose, M.J.; Penas, F.J.; Aguayo, A.T.; Bilbao, J. . Dept. de Ingenieria Quimica)

    1993-11-01

    The application of conical spouted beds with binary mixtures of glass spheres of particle diameters between 1 and 8 mm, in stable operation regime and without segregation, has been studied. The effects of the contactor geometric factors (angle, inlet diameter), of the stagnant bed height, of the mixture composition, and of the gas velocity on bed stability and bed segregation have been analyzed. It has been proven that the correlations proposed in the literature for calculation of the hydrodynamics of spouted beds of cylindrical geometry are not suitable for evaluating the hydrodynamics of the operation with mixtures in conical contactors. Original equations for calculation of the minimum spouting velocity, of the maximum and stable operation pressure drop, and of the bed voidage of minimum spouting have been proposed. In these equations the Sauter mean diameter is used as the characteristic diameter of the mixture. A weighted average value of the (drag force)/(gravity force) ratio is used for calculation of the bed voidage of minimum spouting.

  10. Ion-induced nucleation in a binary mixture

    NASA Technical Reports Server (NTRS)

    Smith, A. C.; Singh, J. J.; Yue, G. K.; Chan, L. Y.

    1982-01-01

    Recent ion-induced nucleation studies in a binary mixture of H2O and H2SO4 vapors indicate that conventional classical nucleation theories cannot account for the experimentally observed ion-H2O-H2SO4 microcluster spectra. An empirical-analytical, semi-molecular theory of nucleation of a binary mixture of vapors on ions has been developed. This theory includes molecular approach to ion-induced changes in dielectric properties in the immediate neighborhood of an ion core as well as the size dependence of the surface tension of the microcluster. In addition to gaseous sulfuric acid and water molecules, the effect of ion-hydrates and sulfuric acid hydrates has also been considered. This theory is further simplified by using an empirical correction factor for the electrostatic term. This correction factor has been obtained by comparing the simplified model with the molecular dynamics calculations for selected ion hydrate formation. These two theoretical models are then compared with the classical theory for a variety of experimental conditions.

  11. Binary mixtures of polyhedral nanoparticles: from phase separation to superstructures

    NASA Astrophysics Data System (ADS)

    Khadilkar, Mihir; Agarwal, Umang; Escobedo, Fernando

    2014-03-01

    Polyhedral nanoparticles have emerged as important model systems for both fundamental studies of entropic self-assembly as well as material design. The mixing of more than one shape provides a promising strategy towards achieving a greater variety of structures and properties. We explore this with the study of the phase behavior of binary mixtures of hard convex polyhedra having similar sizes but different shapes. Choosing representative particle shapes from those readily synthesizable, we find that the phase behavior of such mixtures is dependent on the interplay of mixing and packing entropy, which can give rise to miscible or phase-separated states. While expectedly many of the binary systems studied exhibit phase separation at high pressures due to the incompatible pure-component crystal structures, our study shows that the essential qualitative trends in miscibility and phase separation can be correlated to properties of the pure components, such as the relative values of the order-disorder transition pressure of each component. However, the relative size ratios and the presence of mesophases for the pure-component systems are also critical in aiding the formation of fully miscible blends of novel plastic crystalline superstructures.

  12. Shock Reflection in a Binary Mixture of Noble Gases

    NASA Astrophysics Data System (ADS)

    Whitlock, S. T.; Baganoff, D.

    1996-11-01

    The standard implementation of Bird's Direct Simulation Monte Carlo (DSMC) method for the simulation of multiple-specie flows uses single-specie transport data as input to an ad hoc combining formula to define parameters used in binary collisions between non-like species. To ascertain the suitability of this approach, we focus on the details of translational nonequilibrium in the flow of a binary mixture of noble gases. Existing experimental results for the one-dimensional reflection of a shock wave in a mixture of helium (He) and xenon (Xe) yield a standard of comparison. The molecular weight and diameter of He:Xe are sufficiently disparate so that the relevant time scales of the reflection process are distinct. Simulations are performed on the Intel Paragon using an adaptation of the DSMC method suitable for the parallel computing environment. Using the best characterizations of noble gas intermolecular potentials that have been published to date, we are able to produce simulations of the reflection process which compare favorably with experiment over a range of Xe concentrations. Investigations of various combining rules to arrive at non-like specie collision parameters indicate that any reasonable combining rule works provided that the single-specie data is physically realistic.

  13. Drug-excipient compatibility studies in binary mixtures of avobenzone.

    PubMed

    Ceresole, Rita; Han, Yong K; Rosasco, Maria A; Orelli, Liliana R; Segall, Adriana

    2013-01-01

    During preformulation studies of cosmetic/pharmaceutical products, thermal analysis techniques are very useful to detect physical or chemical incompatibilities between the active and the excipients of interest that might interfere with safety and/or efficacy of the final product. Differential scanning calorimetry (DSC) was used as a screening technique for assessing the compatibility of avobenzone with some currently used cosmetic excipients. In the first phase of the study, DSC was used as a tool to detect any interaction. Based on the DSC results alone, cetearyl alcohol, isopropyl myristate, propylparaben, diethylhexyl syringylidene malonate, caprylic capric triglyceride, butylated hydroxytoluene (BHT), glycerin, cetearyl alcohol/ceteareth 20, cetearyl alcohol/sodium lauryl sulfate/sodium cetearyl sulfate, and paraffinum liquidum exhibit interaction with avobenzone. Stressed binary mixtures (stored at 50°C for 15 days) of avobenzone and excipients were evaluated by high-performance liquid chromatography. Binary mixtures were further investigated by infrared (IR) spectroscopy. Based on DSC, isothermal stress testing, and fourier transform infrared results; avobenzone is incompatible with caprylic capric triglyceride, propylparaben, and BHT.

  14. Phase diagram of highly asymmetric binary hard-sphere mixtures.

    PubMed

    Dijkstra, M; van Roij, R; Evans, R

    1999-05-01

    We study the phase behavior and structure of highly asymmetric binary hard-sphere mixtures. By first integrating out the degrees of freedom of the small spheres in the partition function we derive a formal expression for the effective Hamiltonian of the large spheres. Then using an explicit pairwise (depletion) potential approximation to this effective Hamiltonian in computer simulations, we determine fluid-solid coexistence for size ratios q=0.033, 0.05, 0.1, 0.2, and 1.0. The resulting two-phase region becomes very broad in packing fractions of the large spheres as q becomes very small. We find a stable, isostructural solid-solid transition for q< or =0.05 and a fluid-fluid transition for q< or =0.10. However, the latter remains metastable with respect to the fluid-solid transition for all size ratios we investigate. In the limit q-->0 the phase diagram mimics that of the sticky-sphere system. As expected, the radial distribution function g(r) and the structure factor S(k) of the effective one-component system show no sharp signature of the onset of the freezing transition and we find that at most points on the fluid-solid boundary the value of S(k) at its first peak is much lower than the value given by the Hansen-Verlet freezing criterion. Direct simulations of the true binary mixture of hard spheres were performed for q > or =0.05 in order to test the predictions from the effective Hamiltonian. For those packing fractions of the small spheres where direct simulations are possible, we find remarkably good agreement between the phase boundaries calculated from the two approaches-even up to the symmetric limit q=1 and for very high packings of the large spheres, where the solid-solid transition occurs. In both limits one might expect that an approximation which neglects higher-body terms should fail, but our results support the notion that the main features of the phase equilibria of asymmetric binary hard-sphere mixtures are accounted for by the effective

  15. HPTLC Determination of Three Gliptins in Binary Mixtures with Metformin.

    PubMed

    El-Kimary, Eman I; Hamdy, Dalia A; Mourad, Sara S; Barary, Magda A

    2016-01-01

    A single, simple, selective and validated high performance thin layer chromatographic (HPTLC) method was developed for the determination of either linagliptin (LGP), saxagliptin (SGP) or vildagliptin (VGP) in their binary mixtures with metformin (MET) in pharmaceutical preparations using environmentally preferable green mobile phase system. Separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 using methanol-0.5% w/v aqueous ammonium sulfate (8 : 2, v/v) as mobile phase. Densitometric measurement of the spots was performed at 225 nm for LGP/MET mixture and at 208 nm for both SGP/MET and VGP/MET mixtures. The linear regression analysis data were used for the regression line in the range of 0.05-0.5 µg/band for LGP and SGP and 0.2-2 and 5-40 µg/band for VGP and MET, respectively. The method was validated and showed good performances in terms of linearity, limits of detection and quantitation, precision, accuracy, selectivity and specificity. The calculated percentage relative error values and percentage relative standard deviation for intra- and interday precision studies did not exceed 2%. The developed method was satisfactorily applied for the analysis of pharmaceutical preparations and proved to be specific and accurate for the quality control of the cited drugs in their dosage forms.

  16. Cyclic Segregation State in Vertically Vibrated Binary Granular Mixtures

    NASA Astrophysics Data System (ADS)

    Shi, Qingfan; Pan, Beicheng; Lu, Changhong; Sun, Gang

    2014-01-01

    In this paper, the vertically vibrated binary granular mixtures at atmospheric pressure are studied experimentally. We find a nonstationary segregation state, of which the structure changes with time cyclically. The period of the cyclic segregation is measured and its variation with the vibration conditions is shown. The transition between the segregation states is also discussed, and a phase diagram on the plot of frequency against acceleration amplitude is given. In order to observe the effect of air flow in the segregation process, an alternative container with ventilated bottom is designed. Our experiments show that both regions of the Brazil nut segregation state and the cyclic segregation state shrink obviously by use of the latter container and disappear completely if the whole system is placed in vacuum. These results testify that the air pressure plays a positive role in both the Brazil nut effect and cyclic segregation.

  17. Crystallization kinetics of polydisperse colloidal hard spheres. II. Binary mixtures.

    PubMed

    Martin, S; Bryant, G; van Megen, W

    2005-02-01

    In this paper we present measurements of the crystallization kinetics of binary mixtures of two different sized hard sphere particles. The growth of the Bragg reflections over time were analyzed to yield the crystallite scattering vector, the total amount of crystal, and the average linear crystal size. It was observed that a particle size distribution skewed to higher sized particles has a less detrimental effect on the crystal structure than a skew to smaller sized particles. In the latter case we observe that initial crystallite growth occurs at only a small number of sites, with further crystallization sites developing at later times. Based on these measurements we elaborate further on the previously proposed growth mechanism whereby crystallization occurs in conjunction with a local fractionation process in the fluid, which significantly affects the kinetic growth of crystallites in polydisperse systems.

  18. Phase behaviour of deionized binary mixtures of charged colloidal spheres.

    PubMed

    Lorenz, Nina J; Schöpe, Hans Joachim; Reiber, Holger; Palberg, Thomas; Wette, Patrick; Klassen, Ina; Holland-Moritz, Dirk; Herlach, Dieter; Okubo, Tsuneo

    2009-11-18

    We review recent work on the phase behaviour of binary charged sphere mixtures as a function of particle concentration and composition. Both size ratios Γ and charge ratios Λ are varied over a wide range. Unlike the case for hard spheres, the long-ranged Coulomb interaction stabilizes the crystal phase at low particle concentrations and shifts the occurrence of amorphous solids to particle concentrations considerably larger than the freezing concentration. Depending on Γ and Λ, we observe upper azeotrope, spindle, lower azeotrope and eutectic types of phase diagrams, all known well from metal systems. Most solids are of body centred cubic structure. Occasionally stoichiometric compounds are formed at large particle concentrations. For very low Γ, entropic effects dominate and induce a fluid-fluid phase separation. Since for charged spheres the charge ratio Λ is also decisive for the type of phase diagram, future experiments with charge variable silica spheres are suggested.

  19. Effective potential and interdiffusion in binary ionic mixtures.

    PubMed

    Beznogov, M V; Yakovlev, D G

    2014-09-01

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

  20. Kirkwood-Buff integrals of aqueous alcohol binary mixtures.

    PubMed

    Perera, A; Sokolić, F; Almásy, L; Koga, Y

    2006-03-28

    The Kirkwood-Buff integrals of some binary aqueous alcohol mixtures are computed from the available vapor pressure measurements and compared with previous results as well as small angle neutron scattering experiments. The emphasis of the present report is on accuracy of the results that can be achieved by these two different types of measurements. This seems to be needed, mainly in view of the discrepancies between the various published results, as shown herein. It is argued that agreement in peak positions is more important than that in magnitude. In general, very good agreement is obtained by both methods, and sources of disagreements are discussed. The issue of the computer simulations of aqueous systems and the problematics related to correlations, microheterogeneity, and consequently the Kirkwood-Buff integrals are equally discussed herein.

  1. Theoretical consideration on the acoustic anomaly of critical binary mixtures

    NASA Astrophysics Data System (ADS)

    Tanaka, Hajime; Wada, Yasaku

    1985-07-01

    Existing theories for acoustic anomaly of critical binary mixtures, including both the specific-heat and dynamic-viscosity approach and both mode-coupling and renormalization-group theory, are found to give the same expressions for critical amplitudes of reduced dispersion and absorption after appropriate modifications of the theories from two standpoints: (1) Concentration fluctuations experience the temperature difference from the critical temperature Tc and the sound wave modulates both the temperatures T and Tc and (2) thermodynamic quantities with critical anomaly should be correctly generalized to dynamic ones. The unified expressions of critical amplitudes have not only a temperature dependence but also a frequency dependence, indicating that the dynamic scaling does not hold in an exact sense for the acoustic anomaly. The modified Kroll-Ruhland theory gives new reduced expressions for dispersion and absorption. The difference in scaling functions among various theories is discussed.

  2. Three-dimensional convection of binary mixtures in porous media.

    PubMed

    Umla, R; Augustin, M; Huke, B; Lücke, M

    2011-11-01

    We investigate convection patterns of binary mixtures with a positive separation ratio in porous media. As setup, we choose the Rayleigh-Bénard system of a fluid layer heated from below. Results are obtained by a multimode Galerkin method. Using this method, we compute square and crossroll patterns, and we analyze their structural, bifurcation, and stability properties. Evidence is provided that, for a strong enough Soret effect, both structures exist as stable forms of convection. Some of their properties are found to be similar to square and crossroll convection in the system without porous medium. However, there are also qualitative differences. For example, squares can be destabilized by oscillatory perturbations with square symmetry in porous media, and their velocity isolines are deformed in the so-called Soret regime.

  3. Lattice-Boltzmann-Langevin simulations of binary mixtures.

    PubMed

    Thampi, Sumesh P; Pagonabarraga, Ignacio; Adhikari, R

    2011-10-01

    We report a hybrid numerical method for the solution of the Model H fluctuating hydrodynamic equations for binary mixtures. The momentum conservation equations with Landau-Lifshitz stresses are solved using the fluctuating lattice Boltzmann equation while the order parameter conservation equation with Langevin fluxes is solved using stochastic method of lines. Two methods, based on finite difference and finite volume, are proposed for spatial discretization of the order parameter equation. Special care is taken to ensure that the fluctuation-dissipation theorem is maintained at the lattice level in both cases. The methods are benchmarked by comparing static and dynamic correlations and excellent agreement is found between analytical and numerical results. The Galilean invariance of the model is tested and found to be satisfactory. Thermally induced capillary fluctuations of the interface are captured accurately, indicating that the model can be used to study nonlinear fluctuations.

  4. 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.

  5. Miscibility properties of binary phosphatidylcholine mixtures. A calorimetric study.

    PubMed

    van Dijck, P W; Kaper, A J; Oonk, H A; de Gier, J

    1977-10-03

    From data obtained by differential scanning calorimetry phase diagrams were constructed, using a thermodynamically based fitting method. The following binary mixtures of phosphatidylcholines in water were studied: 14:0/14:0-glycerophosphocholine/16:0/16:0-glucerophosphocholine, 14:0/14:0-glycerophosphocholine/18:0/18:0-glycerophosphocholine, 12:0/12:0-glycerophosphocholine/16:0/16:0-glycerophosphocholine, 18:1t/18:1t-glycerophosphocholine/14:0/14:0-glycerophosphocholine and 18:1t/18:1t-glycerophosphocholine/16:0/16:0-glycerophosphocholine. A comparison is made of the present results with those obtained using probe techniques and the differences are discussed.

  6. Nanofiltration properties of PTMSP in binary organic solvents mixtures

    NASA Astrophysics Data System (ADS)

    Yushkin, A. A.; Kossov, A. A.; Volkov, V. V.

    2016-09-01

    In this study, the stability and nanofiltration performance of poly[1-(trimethylsilyl)- 1-propyne] (PTMSP) in ethanol solutions of butylaldehyde, 1-decanal, 1-hexene, 1-decene was evaluated. It was found that PTMSP was insoluble in all aldehyde solutions, but it was soluble at olefin concentration of 80% or higher. Nanofiltration experiments demonstrate that binary mixtures of 1-decanal and ethanol viscosity are not the parameter affecting on membrane permeability and rejection of solute as well as swelling degree. In the case of decanol/ethanol solutions both solution viscosity and molar volume demonstrate the best fit of experimental data. It was shown that with the decrease of ethanol content in the feed, the rejection of anionic solute Remazol Brilliant Blue R (MW 626) increases from 94 up to 97%.

  7. Turbidity of a Binary Fluid Mixture: Determining Eta

    NASA Technical Reports Server (NTRS)

    Jacobs, Donald T.

    1996-01-01

    A ground based (1-g) experiment is in progress that will measure the turbidity of a density-matched, binary fluid mixture extremely close to its liquid-liquid critical point. By covering the range of reduced temperatures t equivalent to (T-T(sub c)) / T(sub c) from 10(exp -8) to 10(exp -2), the turbidity measurements will allow the critical exponent eta to be determined. No experiment has precisely determined a value of the critical exponent eta, yet its value is significant to theorists in critical phenomena. Relatively simple critical phenomena, as in the liquid-liquid system studied here, serve as model systems for more complex systems near a critical point.

  8. Critical Casimir effect in classical binary liquid mixtures

    NASA Astrophysics Data System (ADS)

    Gambassi, A.; Maciołek, A.; Hertlein, C.; Nellen, U.; Helden, L.; Bechinger, C.; Dietrich, S.

    2009-12-01

    If a fluctuating medium is confined, the ensuing perturbation of its fluctuation spectrum generates Casimir-like effective forces acting on its confining surfaces. Near a continuous phase transition of such a medium the corresponding order parameter fluctuations occur on all length scales and therefore close to the critical point this effect acquires a universal character, i.e., to a large extent it is independent of the microscopic details of the actual system. Accordingly it can be calculated theoretically by studying suitable representative model systems. We report on the direct measurement of critical Casimir forces by total internal reflection microscopy with femtonewton resolution. The corresponding potentials are determined for individual colloidal particles floating above a substrate under the action of the critical thermal noise in the solvent medium, constituted by a binary liquid mixture of water and 2,6-lutidine near its lower consolute point. Depending on the relative adsorption preferences of the colloid and substrate surfaces with respect to the two components of the binary liquid mixture, we observe that, upon approaching the critical point of the solvent, attractive or repulsive forces emerge and supersede those prevailing away from it. Based on the knowledge of the critical Casimir forces acting in film geometries within the Ising universality class and with equal or opposing boundary conditions, we provide the corresponding theoretical predictions for the sphere—planar wall geometry of the experiment. The experimental data for the effective potential can be interpreted consistently in terms of these predictions and a remarkable quantitative agreement is observed.

  9. Critical Casimir effect in classical binary liquid mixtures.

    PubMed

    Gambassi, A; Maciołek, A; Hertlein, C; Nellen, U; Helden, L; Bechinger, C; Dietrich, S

    2009-12-01

    If a fluctuating medium is confined, the ensuing perturbation of its fluctuation spectrum generates Casimir-like effective forces acting on its confining surfaces. Near a continuous phase transition of such a medium the corresponding order parameter fluctuations occur on all length scales and therefore close to the critical point this effect acquires a universal character, i.e., to a large extent it is independent of the microscopic details of the actual system. Accordingly it can be calculated theoretically by studying suitable representative model systems. We report on the direct measurement of critical Casimir forces by total internal reflection microscopy with femtonewton resolution. The corresponding potentials are determined for individual colloidal particles floating above a substrate under the action of the critical thermal noise in the solvent medium, constituted by a binary liquid mixture of water and 2,6-lutidine near its lower consolute point. Depending on the relative adsorption preferences of the colloid and substrate surfaces with respect to the two components of the binary liquid mixture, we observe that, upon approaching the critical point of the solvent, attractive or repulsive forces emerge and supersede those prevailing away from it. Based on the knowledge of the critical Casimir forces acting in film geometries within the Ising universality class and with equal or opposing boundary conditions, we provide the corresponding theoretical predictions for the sphere-planar wall geometry of the experiment. The experimental data for the effective potential can be interpreted consistently in terms of these predictions and a remarkable quantitative agreement is observed.

  10. Particle segregation during explosive dispersal of binary particle mixtures

    NASA Astrophysics Data System (ADS)

    Frost, David L.; Loiseau, Jason; Marr, Bradley J.; Goroshin, Samuel

    2017-01-01

    The explosive dispersal of a layer of solid particles surrounding a spherical high explosive charge generates a turbulent, multiphase flow. The shock-compacted particle layer typically fractures into discrete fragments which move radially outwards on ballistic trajectories. The fragments shed particles in their wakes forming jet-like structures. The tendency to form jets depends on the mass-ratio of the particles to explosive and the type of particles. Brittle or soft, ductile particles are more susceptible to forming jets during compaction and dispersal, whereas particles that are comprised of material with moderate hardness, high compressive strength and high toughness are much less prone to forming jets. Experiments have been carried out to determine the degree of particle segregation that occurs during the explosive dispersal of a uniform, binary mixture containing both "jetting" (silicon carbide) and "non-jetting" (steel) particles with various mass fractions of each particle type. During the dispersal of mixtures that contain predominantly non-jetting (steel) particles, the steel particles form a stable layer whereas the jetting (silicon carbide) particles rapidly segregate and form jets which are confined within the shell of steel particles. As the fraction of silicon carbide particles increases, the jet structures dominate the particle motion and the steel particles are entrained into the jet structures.

  11. Morphological transformations in polymer brushes in binary mixtures: DPD study.

    PubMed

    Cheng, Jianli; Vishnyakov, Aleksey; Neimark, Alexander V

    2014-11-04

    Morphological transformations in polymer brushes in a binary mixture of good and bad solvents are studied using dissipative particle dynamics simulations drawing on a characteristic example of polyisoprene natural rubber in an acetone-benzene mixture. A coarse-grained DPD model of this system is built based on the experimental data in the literature. We focus on the transformation of dense, collapsed brush in bad solvent (acetone) to expanded brush solvated in good solvent (benzene) as the concentration of benzene increases. Compared to a sharp globule-to-coil transition observed in individual tethered chains, the collapsed-to-expanded transformation in brushes is found to be gradual without a prominent transition point. The transformation becomes more leveled as the brush density increases. At low densities, the collapsed brush is highly inhomogeneous and patterned into bunches composed of neighboring chains due to favorable polymer-polymer interaction. At high densities, the brush is expanded even in bad solvent due to steric restrictions. In addition, we considered a model system similar to the PINR-acetone-benzene system, but with the interactions between the solvent components worsened to the limit of miscibility. Enhanced contrast between good and bad solvents facilitates absorption of the good solvent by the brush, shifting the collapsed-to-expanded transformation to lower concentrations of good solvent. This effect is especially pronounced for higher brush densities.

  12. Population annealing simulations of a binary hard-sphere mixture

    NASA Astrophysics Data System (ADS)

    Callaham, Jared; Machta, Jonathan

    2017-06-01

    Population annealing is a sequential Monte Carlo scheme well suited to simulating equilibrium states of systems with rough free energy landscapes. Here we use population annealing to study a binary mixture of hard spheres. Population annealing is a parallel version of simulated annealing with an extra resampling step that ensures that a population of replicas of the system represents the equilibrium ensemble at every packing fraction in an annealing schedule. The algorithm and its equilibration properties are described, and results are presented for a glass-forming fluid composed of a 50/50 mixture of hard spheres with diameter ratio of 1.4:1. For this system, we obtain precise results for the equation of state in the glassy regime up to packing fractions φ ≈0.60 and study deviations from the Boublik-Mansoori-Carnahan-Starling-Leland equation of state. For higher packing fractions, the algorithm falls out of equilibrium and a free volume fit predicts jamming at packing fraction φ ≈0.667 . We conclude that population annealing is an effective tool for studying equilibrium glassy fluids and the jamming transition.

  13. Determination of interfacial tension of binary mixtures from perturbative approaches

    NASA Astrophysics Data System (ADS)

    Martínez-Ruiz, F. J.; Blas, F. J.

    2015-05-01

    We determine the interfacial properties of mixtures of spherical Lennard-Jones molecules from direct simulation of the vapour-liquid interface. We consider mixtures with same molecular size but different dispersive energy parameter values. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janeček, presented recently by MacDowell and Blas and Martínez-Ruiz et al., to deal with the interaction energy and microscopic components of the pressure tensor. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of mixtures of Lennard-Jones molecules with a cut-off distance rc = 3σ in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The vapour-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. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, and interfacial thickness as functions of pressure, at a given temperature. According to our results, the main effect of increasing the ratio between the dispersive energy parameters of the mixture, ε22/ε11, is to sharpen the vapour-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative maximum in the density profiles of the less volatile component at the interface. This maximum is related with adsorption or accumulation of these molecules at the interface, a direct consequence of stronger attractive interactions between these molecules in

  14. Binary Mixtures of Polycyclic Aromatic Hydrocarbons Display Nonadditive Mixture Interactions in an In Vitro Liver Cell Model.

    PubMed

    Gaskill, Stacey J; Bruce, Erica D

    2016-05-01

    Polycyclic aromatic hydrocarbons (PAHs) have been labeled contaminants of concern due to their carcinogenic potential, insufficient toxicological data, environmental ubiquity, and inconsistencies in the composition of environmental mixtures. The Environmental Protection Agency is reevaluating current methods for assessing the toxicity of PAHs, including the assumption of toxic additivity in mixtures. This study was aimed at testing mixture interactions through in vitro cell culture experimentation, and modeling the toxicity using quantitative structure-activity relationships (QSAR). Clone-9 rat liver cells were used to analyze cellular proliferation, viability, and genotoxicity of 15 PAHs in single doses and binary mixtures. Tests revealed that many mixtures have nonadditive toxicity, but display varying mixture effects depending on the mixture composition. Many mixtures displayed antagonism, similar to other published studies. QSARs were then developed using the genetic function approximation algorithm to predict toxic activity both in single PAH congeners and in binary mixtures. Effective concentrations inhibiting 50% of the cell populations were modeled, with R(2) = 0.90, 0.99, and 0.84, respectively. The QSAR mixture algorithms were then adjusted to account for the observed mixture interactions as well as the mixture composition (ratios) to assess the feasibility of QSARs for mixtures. Based on these results, toxic addition is improbable and therefore environmental PAH mixtures are likely to see nonadditive responses when complex interactions occur between components. Furthermore, QSAR may be a useful tool to help bridge these data gaps surrounding the assessment of human health risks that are associated with PAH exposures.

  15. Analysis of using binary cryogenic mixtures containing nitrogen and alkanes or alkenes in cryocoolers

    NASA Astrophysics Data System (ADS)

    Xu, M.; He, Y.; Chen, Z.

    This paper describes the working mechanism of binary cryogenic mixtures containing nitrogen and alkanes or alkenes. The Peng-Robinson equation of state is used to calculate the mixed free enthalpy of these mixtures and a method to calculate the mutual solubility is also suggested. Finally, the vapour-liquid, liquid-liquid and vapourliquid-liquid equilibria of these mixtures are analysed. Therefore, an effective method to predict the characteristics of new kinds of binary cryogenic substances is provided in this paper.

  16. Assessment and prediction of joint algal toxicity of binary mixtures of graphene and ionic liquids.

    PubMed

    Wang, Zhuang; Zhang, Fan; Wang, Se; Peijnenburg, Willie J G M

    2017-10-01

    Graphene and ionic liquids (ILs) released into the environment will interact with each other. So far however, the risks associated with the concurrent exposure of biota to graphene and ILs in the environment have received little attention. The research reported here focused on observing and predicting the joint toxicity effects in the green alga Scenedesmus obliquus exposed to binary mixtures of intrinsic graphene (iG)/graphene oxide (GO) and five ILs of varying anionic and cationic types. The isolated ILs in the binary mixtures were the main contributors to toxicity. The binary GO-IL mixtures resulted in more severe joint toxicity than the binary iG-IL mixtures, irrespective of mixture ratios. The mechanism of the joint toxicity may be associated with the adsorption capability of the graphenes for the ILs, the dispersion stability of the graphenes in aquatic media, and modulation of the binary mixtures-induced oxidative stress. A toxic unit assessment showed that the graphene and IL toxicities were additive at low concentration of the mixtures but antagonistic at high concentration of the mixtures. Predictions made using the concentration addition and independent action models were close to the observed joint toxicities regardless of mixture types and mixture ratios. These findings provide new insights that are of use in the risk assessment of mixtures of engineered nanoparticles and other environmentally relevant contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Perturbation Theory of Large-Particle Diffusion in a Binary Solvent Mixture

    NASA Astrophysics Data System (ADS)

    Nakamura, Yuka; Yoshimori, Akira; Akiyama, Ryo

    2014-06-01

    We study the diffusion of a large spherical particle immersed in a binary compressive liquid mixture using a perturbation theory. We focus on the breakdown of the Stokes-Einstein (SE) relation caused by the microscopic solvation structure of binary solvent particles around a solute particle. In order to consider the solvation structure, we solve multicomponent generalized Langevin equations by singular perturbation expansion. Then, we assume that solvent particles are much smaller than the solute particle. Solving the equations, we express the diffusion coefficient analytically using the radial distribution functions of a binary mixture. The expression shows the breakdown of the SE relation if the density distribution of a binary solvent is inhomogeneous around a solute particle. Actually, we show that the SE relation breaks down when a large hard sphere diffuses in a binary hard-sphere mixture. We observe the large deviation from the SE relation, which is a result specific to the binary solvent.

  18. Dissipation process of binary gas mixtures in thermally relativistic flow

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2016-04-01

    In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier-Stokes-Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165-74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.

  19. Decomposition and interface evolution in films of binary mixtures

    NASA Astrophysics Data System (ADS)

    Madruga, Santiago; Bribesh, Fathi; Thiele, Uwe

    2011-11-01

    Model-H describes the coupled transport of concentration and momentum in binary mixtures such as polymer blends. Films of polymer blends are used in technological applications that involve coatings or the creation of structural functional layers. We use an extended version of the model-H for free evolving surfaces to analyze the stability of vertically stratified base states of polymer blends on a solid substrate. We determine the bifurcation diagram of the films by studying their free energy, and L2-norms of surface deflection and concentration field. We provide results for selected mean film thickness with and without energetic bias at the free surface and discuss the role of composition in extended and laterally bounded systems. In addition, we show that the inclusion of convective transport leads to new mechanisms of instability as compared to the purely diffusive case,. S.M. acknowledges support via FP7 Marie Curie Reintegration Grant (PERG04-GA-2008-234384), and U.T. by EU via FP7 (PITN-GA-2008-214919).

  20. Pattern formation in granular binary mixtures under shear flow

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Narteau, Clement; Rozier, Olivier

    2013-04-01

    We study numerically the formation and evolution of bed forms using a binary granular mixture. The two types of particles may have different dynamic properties and angle of repose. We associate these changes to two different grain sizes, the so-called coarse and thin particles. Our computation are based on a real-space cellular automaton that combines a model of sediment transport with a lattice-gas cellular automaton. Thus, we implement the permanent feedbacks between fluid flow and topography. Keeping constant the strength of the flow, we explore a parameter-space by varying the size of the coarse particles and their proportion within the bed. As a result of avalanches and sediment transport, we systematically find regions of segregation and stratification. In a vast majority of cases, we also observe the formation of an armoring layer mainly composed of coarse particles. Its depth is mainly controlled by the proportion of coarse grains and not by the size of these larger particles. When there is a larger proportion of thin particles, transverse dunes develop on the top of the armoring layer. As this proportion decreases, we may observe barchans or even no clear bed forms. We conclude that the main control parameter for dune pattern formation is the thin sediment availability. Finally, we discuss the processes responsible for the formation of the armoring layer and show how it controls the overall sediment transport.

  1. Superlattice Formation in Binary Mixtures of Block Copolymer Micelles

    SciTech Connect

    Abbas, Sayeed; Lodge, Timothy P.

    2008-08-26

    Two distinct diblock copolymers, poly(styrene-b-isoprene) (SI) and poly(styrene-b-dimethylsiloxane) (SD), were codissolved at various concentrations in the polystyrene selective solvent diethyl phthalate. Two SI diblocks, with block molar masses of 12000-33000 and 30000-33000, and two SD diblocks, with block molar masses of 19000-6000 and 16000-9000, were employed. The size ratio of the smaller SD micelles (S) to the larger SI micelles (L) varied from approximately 0.5 to 0.6, based on hydrodynamic radii determined by dynamic light scattering on dilute solutions containing only one polymer component. Due to incompatibility between the polyisoprene and polydimethylsiloxane blocks, a binary mixture of distinct SI and SD micelles was formed in each mixed solution, as confirmed by cryogenic transmission electron microscopy. When the total concentration of polymer was increased to 20--30%, the micelles adopted a superlattice structure. Small angle X-ray scattering revealed the lattice to be the full LS{sub 13} superlattice (space group Fm{sub 3}c) in all cases, with unit cell dimensions in excess of 145 nm. A coexistent face-centered cubic phase composed of SD micelles was also observed when the number ratio of S to L micelles was large.

  2. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, S.R.; Christophorou, L.G.

    1988-04-27

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

  3. Foam fractionation of binary mixtures of lysozyme and albumin.

    PubMed

    Lockwood, C E; Jay, M; Bummer, P M

    2000-06-01

    A nitrogen gas-based foam fractionation method was employed to separate model proteins, bovine serum albumin (BSA) and hen egg white lysozyme, from each other. Fractionation was characterized by the separation ratio and by recovery of proteins in the retentate as a function of the nominal pore size of the gas dispersion frit and solution conditions (pH and ionic strength). For binary mixtures of the proteins at pH 7.4, and ionic strength (mu) of 0.18 M, the recovery of lysozyme and the separation ratio were both dependent on the frit size employed to generate the foam. At low ionic strength (mu = 0.01 M), separation was only somewhat greater with the small pore size frits, although at values significantly lower than those found for high ionic strength. The diminished separations appear to be due to the only slight changes in recoveries observed for BSA and lysozyme.%Separation ratios of lysozyme from BSA in solutions either of high or low ionic strength were maximal at pH values equal to or less than the isoelectric point (pI) of BSA. Separation ratios were lower when foaming was carried out under low compared with high ionic strength. The recovery of lysozyme was enhanced by foaming from solutions of low pH and high ionic strength. Recoveries of BSA were greatest when the molecule was negatively charged. Electrical interactions between the positively charged lysozyme and negatively charged BSA may explain the diminished separation ratios and enhanced recoveries. Enzyme activity studies of lysozyme remaining in the retentate showed no change from prefoam activity.

  4. Collective motion of binary self-propelled particle mixtures.

    PubMed

    Menzel, Andreas M

    2012-02-01

    In this study, we investigate the phenomenon of collective motion in binary mixtures of self-propelled particles. More precisely, we consider two particle species, each of which consisting of pointlike objects that propel with a velocity of constant magnitude. Within each species, the particles try to achieve polar alignment of their velocity vectors, whereas we analyze the cases of preferred polar, antiparallel, as well as perpendicular alignment between particles of different species. Our focus is on the effect that the interplay between the two species has on the threshold densities for the onset of collective motion and on the nature of the solutions above onset. For this purpose, we start from suitable Langevin equations in the particle picture, from which we derive mean field equations of the Fokker-Planck type and finally macroscopic continuum field equations. We perform particle simulations of the Langevin equations and linear stability analyses of the Fokker-Planck and macroscopic continuum equations, and we numerically solve the Fokker-Planck equations. Both spatially homogeneous and inhomogeneous solutions are investigated, where the latter correspond to stripelike flocks of collectively moving particles. In general, the interaction between the two species reduces the threshold density for the onset of collective motion of each species. However, this interaction also reduces the spatial organization in the stripelike flocks. The case that shows the most interesting behavior is the one of preferred perpendicular alignment between different species. There a competition between polar and truly nematic orientational ordering of the velocity vectors takes place within each particle species. Finally, depending on the alignment rule for particles of different species and within certain ranges of particle densities, identical and inverted spatial density profiles can be found for the two particle species. The system under investigation is confined to two spatial

  5. Pattern formation in granular binary mixtures under shear flow

    NASA Astrophysics Data System (ADS)

    Gao, X.; Narteau, C.; Rozier, O.

    2012-12-01

    Polydisperse granular materials are ubiquitous in the field of geomorphology. Nevertheless, it remains a challenge to address the impact of segregation, stratification and mixing on landscape dynamics and sediment transport. Here, we study numerically the formation and evolution of bed forms using a binary granular mixture. The two types of particles may have different dynamic properties and angle of repose. We associate these changes to two different grain sizes, the so-called coarse and thin particles. Our computation are based on a real-space cellular automaton that combines a model of sediment transport with a lattice-gas cellular automaton. Thus, we implement the permanent feedbacks between fluid flow and topography. Keeping constant the strength of the flow, we explore a parameter-space by varying the size of the coarse particles and their proportion within the bed. As a result of avalanches and sediment transport, we systematically find regions of segregation and stratification. In a vast majority of cases, we also observe the formation of an armoring layer mainly composed of coarse particles. Its depth is mainly controlled by the proportion of coarse grains and not by the size of these larger particles. When there is a larger proportion of thin particles, transverse dunes develop on the top of the armoring layer. As this proportion decreases, we may observe barchans or even no clear bed forms. Not surprisingly, we conclude that the main control parameter for dune pattern formation is the thin sediment availability. Finally, we discuss the processes responsible for the formation of the armoring layer and show how it controls the overall sediment transport.

  6. Bubble-Point Measurements of n-Propane + n-Decane Binary Mixtures with Comparisons of Binary Mixture Interaction Parameters for Linear Alkanes.

    PubMed

    Mansfield, Elisabeth; Bell, Ian H; Outcalt, Stephanie L

    2016-07-14

    To develop comprehensive models for multicomponent natural gas mixtures, it is necessary to have binary interaction parameters for each of the pairs of constituent fluids that form the mixture. The determination of accurate mixture interaction parameters depends on reliably collected experimental data. In this work, we have carried out an experimental campaign to measure the bubble-point pressures of mixtures of n-propane and n-decane, a mixture that has been thus far poorly studied with only four existing data sets. The experimental measurements of bubble-point states span a composition range (in n-propane mole fraction) from 0.269 to 0.852, and the bubble-point pressures are measured in the temperature range from 270 K to 370 K. These data, in conjunction with data from a previous publication on mixtures of n-butane + n-octane and n-butane + n-nonane, are used to determine binary interaction parameters. The newly-obtained binary interaction parameters for the mixture of n-propane and n-decane represent the experimental bubble-point pressures given here to within 8% (coverage factor, k=2), as opposed to previous deviations up to 19%.

  7. Computer simulation-molecular-thermodynamic framework to predict the micellization behavior of mixtures of surfactants: application to binary surfactant mixtures.

    PubMed

    Iyer, Jaisree; Mendenhall, Jonathan D; Blankschtein, Daniel

    2013-05-30

    We present a computer simulation-molecular-thermodynamic (CSMT) framework to model the micellization behavior of mixtures of surfactants in which hydration information from all-atomistic simulations of surfactant mixed micelles and monomers in aqueous solution is incorporated into a well-established molecular-thermodynamic framework for mixed surfactant micellization. In addition, we address the challenges associated with the practical implementation of the CSMT framework by formulating a simpler mixture CSMT model based on a composition-weighted average approach involving single-component micelle simulations of the mixture constituents. We show that the simpler mixture CSMT model works well for all of the binary surfactant mixtures considered, except for those containing alkyl ethoxylate surfactants, and rationalize this finding molecularly. The mixture CSMT model is then utilized to predict mixture CMCs, and we find that the predicted CMCs compare very well with the experimental CMCs for various binary mixtures of linear surfactants. This paper lays the foundation for the mixture CSMT framework, which can be used to predict the micellization properties of mixtures of surfactants that possess a complex chemical architecture, and are therefore not amenable to traditional molecular-thermodynamic modeling.

  8. MULTISUBSTRATE BIODEGRADATION KINETICS FOR BINARY AND COMPLEX MIXTURES OF POLYCYCLIC AROMATIC HYDROCARBONS

    EPA Science Inventory

    Biodegradation kinetics were studied for binary and complex mixtures of nine polycyclic aromatic hydrocarbons (PAHs): naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2-ethylnaphthalene, phenanthrene, anthracene, pyrene, fluorene and fluoranthene. Discrepancies between the ...

  9. MULTISUBSTRATE BIODEGRADATION KINETICS FOR BINARY AND COMPLEX MIXTURES OF POLYCYCLIC AROMATIC HYDROCARBONS

    EPA Science Inventory

    Biodegradation kinetics were studied for binary and complex mixtures of nine polycyclic aromatic hydrocarbons (PAHs): naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2-ethylnaphthalene, phenanthrene, anthracene, pyrene, fluorene and fluoranthene. Discrepancies between the ...

  10. Analysis of binary cryogenic mixtures containing nitrogen and Freon in cryocoolers

    NASA Astrophysics Data System (ADS)

    Xu, Mingyao; He, Yaling; Chen, Zhongqi

    Several new non-inflammable binary cryogenic mixtures of nitrogen and Freon are suggested in this paper. The working mechanism of using these mixtures in a Joule-Thomson cryocooler is analysed according to thermodynamic theory. The Peng-Robinson equation of state is used to calculate the mixed free enthalpy of these mixtures and a method to calculate the mutual solubility is also suggested. Finally, the vapour-liquid equilibria, liquid-liquid equilibria and vapour-liquid-liquid equilibria of these mixtures are analysed. It is shown that the suggested mixtures can be used as alternatives to mixtures of nitrogen and alkanes or alkenes.

  11. Compound valence is conserved in binary odor mixtures in Drosophila melanogaster.

    PubMed

    Thoma, Michael; Hansson, Bill S; Knaden, Markus

    2014-10-15

    Most naturally occurring olfactory signals do not consist of monomolecular odorants but, rather, are mixtures whose composition and concentration ratios vary. While there is ample evidence for the relevance of complex odor blends in ecological interactions and for interactions of chemicals in both peripheral and central neuronal processing, a fine-scale analysis of rules governing the innate behavioral responses of Drosophila melanogaster towards odor mixtures is lacking. In this study we examine whether the innate valence of odors is conserved in binary odor mixtures. We show that binary mixtures of attractants are more attractive than individual mixture constituents. In contrast, mixing attractants with repellents elicits responses that are lower than the responses towards the corresponding attractants. This decrease in attraction is repellent-specific, independent of the identity of the attractant and more stereotyped across individuals than responses towards the repellent alone. Mixtures of repellents are either less attractive than the individual mixture constituents or these mixtures represent an intermediate. Within the limits of our data set, most mixture responses are quantitatively predictable on the basis of constituent responses. In summary, the valence of binary odor mixtures is predictable on the basis of valences of mixture constituents. Our findings will further our understanding of innate behavior towards ecologically relevant odor blends and will serve as a powerful tool for deciphering the olfactory valence code.

  12. Convection in binary fluid mixtures. II. Localized traveling waves

    NASA Astrophysics Data System (ADS)

    Barten, W.; Lücke, M.; Kamps, M.; Schmitz, R.

    1995-06-01

    Nonlinear, spatially localized structures of traveling convection rolls that are surrounded by quiescent fluid in horizontal layers of binary fluids heated from below are investigated in quantitative detail as a function of Rayleigh number for two different Soret coupling strengths (separation ratios) with Lewis and Prandtl numbers characterizing ethanol-water mixtures. A finite-difference method was used to solve the full hydrodynamic field equations numerically in a vertical cross section perpendicular to the roll axes subject to realistic horizontal and laterally periodic boundary conditions with different periodicity lengths. Structure and dynamics of these localized traveling waves (LTW's) are dominated by the concentration field. As in the spatially extended convective states that are investigated in an accompanying paper, the Soret-induced concentration variations strongly influence, via density changes, the buoyancy forces that drive convection. The spatiotemporal properties of this feedback mechanism, involving boundary layers and concentration plumes, show that LTW's are strongly nonlinear states. Light intensity distributions are determined that can be observed in side-view shadowgraphs done with horizontal light along the roll axes. Detailed analyses of all fields are made using color-coded isoplots, among others. In the frame comoving with their drift velocity, LTW's display a nontrivial spatiotemporal symmetry consisting of time translation by one-half an oscillation period combined with vertical reflection through the horizontal midplane of the layer. A time-averaged concentration current is driven by a phase difference between the waves of concentration and vertical velocity in the bulk of the LTW state. The associated large-scale concentration redistribution stabilizes the LTW and controls its drift velocity into the quiescent fluid by generating a buoyancy-reducing concentration ``barrier'' ahead of the leading LTW front. All considered LTW

  13. Raman Spectroscopy Study of Solvation Structure in Acetonitrile/Water Mixtures

    DTIC Science & Technology

    1991-04-22

    in liquid 120). sENO9 ! F,,r comparison. the boiling point of methanol i similar densitv :i and moiecular weight). which exists as a hydrogen - bonded ...microenvironment.PARfl ,EN03 i The CN stretch in acetonitrile exhibits a rather unique shift IIti higher frequency vnen hydrogen bonded 113) or coordi...frequencies when CHCN is hydrogen oonded 113. 19).PARI2 sENO3 I The liquid structure of CHC.N is alto of interest and re- SENe 12 mains unresolved. Strong

  14. Forage production of grass-legume binary mixtures on Intermountain Western USA irrigated pastures

    USDA-ARS?s Scientific Manuscript database

    A well-managed irrigated pasture is optimized for forage production with the use of N fertilizer which incurs extra expense. The objective was to determine which binary grass-legume mixture and mixture planting ratio of tall fescue (Festuca arundinacea Schreb.) (TF), meadow brome (Bromus bieberstei...

  15. A semiempirical method for analysis of the reflectance spectra of binary mineral mixtures

    NASA Technical Reports Server (NTRS)

    Johnson, P. E.; Smith, M. O.; Taylor-George, S.; Adams, J. B.

    1983-01-01

    A simple semiempirical method is presented for determination of the spectral reflectance of a powdered binary mineral mixture. This technique uses a two-stream radiative transfer model (a modified Kubelka-Munk model) on a particulate medium of isotroic scatterers The particles are assumed to be much larger than the wavelength of light under consideration. This same method can be used to determine the relative proportion of components in a mixture for which the spectral reflectance is known. Binary mixtures of olivine, two pyroxenes, and magnetite are used to test this model. The theoretical and empirical results agree approximately within experimental errors.

  16. Surface analysis of powder binary mixtures with ATR FTIR spectroscopy.

    PubMed

    Planinsek, Odon; Planinsek, Daniela; Zega, Anamarija; Breznik, Matej; Srcic, Stane

    2006-08-17

    Attenuated Total Reflectance Fourier Transform Infra Red spectroscopy (ATR FTIR) has been used for surface analysis of powder mixtures. The appearance of one component on the surface of the mixture in greater amounts than that expected from the mass or volume ratio was quantified. Coloured mixtures containing methyl orange were analysed. They contained proportions of components from 0% to 100% in steps of 10%. Mixtures of non-sieved powders of methyl orange and Povidone were dark red when containing only 20% of methyl orange, indicating that particles of methyl orange were present on the surface of the mixture in higher amounts than expected from the mass ratios. Mixtures of methyl orange and Mg stearate, on the other hand, were a light colour, showing the presence of more Mg stearate on the surface than expected. Visual observations correlated with semiquantitative surface concentration determination by ATR FTIR spectroscopy using specific peaks of each component. Quantitative determination of components on the surface of the mixture, using the Beer Lambert law, was possible when characteristic peaks for the first component did not overlap with those of the other component. A non-linear correlation between peak height and concentration of a component in a mixture was explained by distribution of the particle size of components. With a small component, the larger number of particles in the same volume allowed them to surround the larger particles of the second component. These conclusions were confirmed by preparing mixtures with non-coloured components (Povidone-Eudragit, NaCl-Povidone, NaCl-Eudragit. Results again correlated with the ATR FTIR spectroscopy measurements. It was additionally shown that a small proportion of finer particles can drastically influence the surface of powder mixtures, due to their large contribution to the specific surface area. ATR FTIR is thus demonstrated to be a useful method for studying surfaces of powder mixtures also in terms of

  17. Using Delaunay triangulation and Voronoi tessellation to predict the toxicities of binary mixtures containing hormetic compound

    NASA Astrophysics Data System (ADS)

    Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong

    2017-03-01

    Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures.

  18. Using Delaunay triangulation and Voronoi tessellation to predict the toxicities of binary mixtures containing hormetic compound

    PubMed Central

    Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong

    2017-01-01

    Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures. PMID:28287626

  19. Using Delaunay triangulation and Voronoi tessellation to predict the toxicities of binary mixtures containing hormetic compound.

    PubMed

    Qu, Rui; Liu, Shu-Shen; Zheng, Qiao-Feng; Li, Tong

    2017-03-13

    Concentration addition (CA) was proposed as a reasonable default approach for the ecological risk assessment of chemical mixtures. However, CA cannot predict the toxicity of mixture at some effect zones if not all components have definite effective concentrations at the given effect, such as some compounds induce hormesis. In this paper, we developed a new method for the toxicity prediction of various types of binary mixtures, an interpolation method based on the Delaunay triangulation (DT) and Voronoi tessellation (VT) as well as the training set of direct equipartition ray design (EquRay) mixtures, simply IDVequ. At first, the EquRay was employed to design the basic concentration compositions of five binary mixture rays. The toxic effects of single components and mixture rays at different times and various concentrations were determined by the time-dependent microplate toxicity analysis. Secondly, the concentration-toxicity data of the pure components and various mixture rays were acted as a training set. The DT triangles and VT polygons were constructed by various vertices of concentrations in the training set. The toxicities of unknown mixtures were predicted by the linear interpolation and natural neighbor interpolation of vertices. The IDVequ successfully predicted the toxicities of various types of binary mixtures.

  20. TOXICOKINETIC INTERACTIONS AND SURVIVAL OF HYALELLA AZTECA EXPOSED TO BINARY MIXTURES OF CHLORPYRIFOS, DIELDRIN, AND METHYL MERCURY

    EPA Science Inventory

    Chemical mixture interactions of chlorpyrifos, dieldrin, and methyl mercury were evaluated in Hyalella azteca. Survival of adult and juvenile organisms was evaluated following exposure to individual chemicals and in binary combinations. Binary interactions of the model chemicals...

  1. Heterogeneity in binary mixtures of dimethyl sulfoxide and glycerol: fluorescence correlation spectroscopy.

    PubMed

    Chattoraj, Shyamtanu; Chowdhury, Rajdeep; Ghosh, Shirsendu; Bhattacharyya, Kankan

    2013-06-07

    Diffusion of four coumarin dyes in a binary mixture of dimethyl sulfoxide (DMSO) and glycerol is studied using fluorescence correlation spectroscopy (FCS). The coumarin dyes are C151, C152, C480, and C481. In pure DMSO, all the four dyes exhibit a very narrow (almost uni-modal) distribution of diffusion coefficient (Dt). In contrast, in the binary mixtures all of them display a bimodal distribution of Dt with broadly two components. One of the components of D(t) corresponds to the bulk viscosity. The other one is similar to that in pure DMSO. This clearly indicates the presence of two distinctly different nano-domains inside the binary mixture. In the first, the micro-environment of the solute consists of both DMSO and glycerol approximately at the bulk composition. The other corresponds to a situation where the first layer of the solute consists of DMSO only. The burst integrated fluorescence lifetime (BIFL) analysis also indicates presence of two micro-environments one of which resembles DMSO. The relative contribution of the DMSO-like environment obtained from the BIFL analysis is much larger than that obtained from FCS measurements. It is proposed that BIFL corresponds to an instantaneous environment in a small region (a few nm) around the probe. FCS, on the contrary, describes the long time trajectory of the probes in a region of dimension ~200 nm. The results are explained in terms of the theory of binary mixtures and recent simulations of binary mixtures containing DMSO.

  2. Theoretical Analysis of Heat Pump Cycle Characteristics with Pure Refrigerants and Binary Refrigerant Mixtures

    NASA Astrophysics Data System (ADS)

    Kagawa, Noboru; Uematsu, Masahiko; Watanabe, Koichi

    In recent years there has been an increasing interest of the use of nonazeotropic binary mixtures to improve performance in heat pump systems, and to restrict the consumption of chlorofluorocarbon (CFC) refrigerants as internationally agreed-upon in the Montreal Protocol. However, the available knowledge on the thermophysical properties of mixtures is very much limited particularly with respect to quantitative information. In order to systematize cycle performance with Refrigerant 12 (CCl2F2) + Refrigerant 22 (CHClF2) and Refrigerant 22 + Refrigerant 114 (CClF2-CClF2) systems which are technically important halogenated refrigerant mixtures, the heat pump cycle analysis in case of using these mixtures was theoretically studied. It became clear that the maximum coefficients of performance with various pure refrigerants and binary refrigerant mixtures were obtained at the reduced condensing temperature being 0.9 when the same temperature difference between condensing and evaporating temperature was chosen.

  3. Hydrogen component fugacity coefficients in binary mixtures with ethane: Pressure dependence

    NASA Astrophysics Data System (ADS)

    Bruno, T. J.; Schroeder, J. A.; Outcalt, S. L.

    1990-09-01

    The fugacity coefficients of hydrogen in binary mixtures with ethane were measured. Data were taken using an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not ethane, can penetrate. The measurement of the gas pressures inside and outside the membrane gives the hydrogen component fugacity at a given temperature, binary mixture mole fraction, and mixture pressure. In this paper, results are reported at mixture pressures of 5.25, 6.97, 10.21, and 13.47 MPa. In each case, the temperature of the mixture was maintained at an average value of 130°C (403.15 K). The general qualitative features of the data are discussed, and comparisons are made with predictions obtained from the Redlich-Kwong and Peng-Robinson equations of state.

  4. Probing Intermolecular Interactions in Binary Liquid Mixtures Using Femtosecond Laser-Induced Self-Defocusing.

    PubMed

    Maurya, Sandeep Kumar; Das, Dhiman; Goswami, Debabrata

    2016-06-13

    Photo-thermal behavior of binary liquid mixtures has been studied by high repetition rate (HRR) Z-scan technique with femtosecond laser pulses. Changes in the peak-valley difference in transmittance (ΔTP-V) for closed aperture Z-scan experiments are indicative of thermal effects induced by HRR femtosecond laser pulses. We show such indicative results can have a far-reaching impact on molecular properties and intermolecular interactions in binary liquid mixtures. Spectroscopic parameters derived from this experimental technique show that the combined effect of physical and molecular properties of the constituent binary liquids can be related to the components of the binary liquid. © The Author(s) 2016.

  5. Chemical composition and binary mixture of human urinary stones using FT-Raman spectroscopy method.

    PubMed

    Selvaraju, R; Raja, A; Thiruppathi, G

    2013-10-01

    In the present study the human urinary stones were observed in their different chemical compositions of calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, struvite (magnesium ammonium phosphate), uric acid, cystine, oxammite (ammonium oxalate monohydrate), natroxalate (sodium oxalate), glushinkite (magnesium oxalate dihydrate) and moolooite (copper oxalate) were analyzed using Fourier Transform-Raman (FT-Raman) spectroscopy. For the quantitative analysis, various human urinary stone samples are used for ratios calculation of binary mixtures compositions such as COM/COD, HAP/COD, HAP/COD, Uric acid/COM, uric acid/COD and uric acid/HAP. The calibration curve is used for further analysis of binary mixture of human urinary stones. For the binary mixture calculation the various intensities bands at 1462 cm(-1) (I(COM)), 1473 cm(-1) (I(COD)), 961 cm(-1) (I(HAP)) and 1282 cm(-1) (I(UA)) were used.

  6. Thermodynamic coarsening arrested by viscous fingering in partially miscible binary mixtures

    NASA Astrophysics Data System (ADS)

    Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

    2016-09-01

    We study the evolution of binary mixtures far from equilibrium, and show that the interplay between phase separation and hydrodynamic instability can arrest the Ostwald ripening process characteristic of nonflowing mixtures. We describe a model binary system in a Hele-Shaw cell using a phase-field approach with explicit dependence of both phase fraction and mass concentration. When the viscosity contrast between phases is large (as is the case for gas and liquid phases), an imposed background flow leads to viscous fingering, phase branching, and pinch off. This dynamic flow disorder limits phase growth and arrests thermodynamic coarsening. As a result, the system reaches a regime of statistical steady state in which the binary mixture is permanently driven away from equilibrium.

  7. Packing densification of binary mixtures of spheres and cubes subjected to 3D mechanical vibrations

    NASA Astrophysics Data System (ADS)

    An, X. Z.; He, S. S.; Feng, H. D.; Qian, Q.

    2015-01-01

    Packing densification of binary mixtures of spheres and cubes, which are large cubes/small spheres and large spheres/small cubes packing systems, under 3D vibrations was studied physically. The influences of vibration conditions such as vibration time, frequency, amplitude, vibration intensity, volume fraction of large particles, and container size on the packing densification were systematically analyzed, and the optimal processing parameters were identified. And the proposed analytical model was validated as well. The results show that the influences of each operating parameter on the packing densification of different binary mixtures have similar trends; however, the maximum packing densities and corresponding optimal parameters are different. The good agreement between physical and analytical results proves the effectiveness of the proposed analytical model. The results provide meaningful information and references for the random dense packings of binary mixtures of cubes and spheres both in industry and in scientific research.

  8. Prediction of surface tension of binary mixtures with the parachor method

    NASA Astrophysics Data System (ADS)

    Němec, Tomáš

    2015-05-01

    The parachor method for the estimation of the surface tension of binary mixtures is modified by considering temperature-dependent values of the parachor parameters. The temperature dependence is calculated by a least-squares fit of pure-solvent surface tension data to the binary parachor equation utilizing the Peng-Robinson equation of state for the calculation of equilibrium densities. A very good agreement between experimental binary surface tension data and the predictions of the modified parachor method are found for the case of the mixtures of carbon dioxide and butane, benzene, and cyclohexane, respectively. The surface tension is also predicted for three refrigerant mixtures, i.e. propane, isobutane, and chlorodifluoromethane, with carbon dioxide.

  9. Binary and ternary adsorption of n-alkane mixtures on activated carbon

    SciTech Connect

    Kalies, G.; Braeuer, P.; Messow, U.

    1999-06-15

    The adsorption isotherms of the binary n-alkane mixtures n-hexane/n-octane, n-octane/n-tetradecane, and n-hexane/n-tetradecane on the activated carbon TA 95 are measured at 298 K and described with mathematical functions. About 40 experimental values of the adsorption excess of the ternary mixture n-hexane/n-octane/n-tetradecane on activated carbon TA 95 at 298 K are gas chromatographically measured inside the ternary triangle. The ternary data are represented in the three-dimensional space with the help of transformation of coordinates and by utilization of the conception of the quasi-two-component representation of the mole fractions. A consistency test for the specific wetting Gibbs energies calculated from the binary data is carried out. The possibilities for a mathematical prediction of ternary data from adsorption data for the constituent binary mixtures are proved.

  10. Chemical composition and binary mixture of human urinary stones using FT-Raman spectroscopy method

    NASA Astrophysics Data System (ADS)

    Selvaraju, R.; Raja, A.; Thiruppathi, G.

    2013-10-01

    In the present study the human urinary stones were observed in their different chemical compositions of calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, struvite (magnesium ammonium phosphate), uric acid, cystine, oxammite (ammonium oxalate monohydrate), natroxalate (sodium oxalate), glushinkite (magnesium oxalate dihydrate) and moolooite (copper oxalate) were analyzed using Fourier Transform-Raman (FT-Raman) spectroscopy. For the quantitative analysis, various human urinary stone samples are used for ratios calculation of binary mixtures compositions such as COM/COD, HAP/COD, HAP/COD, Uric acid/COM, uric acid/COD and uric acid/HAP. The calibration curve is used for further analysis of binary mixture of human urinary stones. For the binary mixture calculation the various intensities bands at 1462 cm-1 (ICOM), 1473 cm-1 (ICOD), 961 cm-1 (IHAP) and 1282 cm-1 (IUA) were used.

  11. High-frequency sound wave propagation in binary gas mixtures flowing through microchannels

    NASA Astrophysics Data System (ADS)

    Bisi, M.; Lorenzani, S.

    2016-05-01

    The propagation of high-frequency sound waves in binary gas mixtures flowing through microchannels is investigated by using the linearized Boltzmann equation based on a Bhatnagar-Gross-Krook (BGK)-type approach and diffuse reflection boundary conditions. The results presented refer to mixtures whose constituents have comparable molecular mass (like Ne-Ar) as well as to disparate-mass gas mixtures (composed of very heavy plus very light molecules, like He-Xe). The sound wave propagation model considered in the present paper allows to analyze the precise nature of the forced-sound modes excited in different gas mixtures.

  12. Thermodynamic properties and diffusion of water + methane binary mixtures

    SciTech Connect

    Shvab, I.; Sadus, Richard J.

    2014-03-14

    Thermodynamic and diffusion properties of water + methane mixtures in a single liquid phase are studied using NVT molecular dynamics. An extensive comparison is reported for the thermal pressure coefficient, compressibilities, expansion coefficients, heat capacities, Joule-Thomson coefficient, zero frequency speed of sound, and diffusion coefficient at methane concentrations up to 15% in the temperature range of 298–650 K. The simulations reveal a complex concentration dependence of the thermodynamic properties of water + methane mixtures. The compressibilities, heat capacities, and diffusion coefficients decrease with increasing methane concentration, whereas values of the thermal expansion coefficients and speed of sound increase. Increasing methane concentration considerably retards the self-diffusion of both water and methane in the mixture. These effects are caused by changes in hydrogen bond network, solvation shell structure, and dynamics of water molecules induced by the solvation of methane at constant volume conditions.

  13. Undergraduate experiment in critical phenomena. II. The coexistence curve of a binary fluid mixture

    NASA Astrophysics Data System (ADS)

    Ngubane, S. B.; Jacobs, D. T.

    1986-06-01

    An undergraduate experiment is described that uses meniscus heights to determine the coexistence curve of a binary fluid mixture. The data can be obtained with a minimum of equipment and yield results that are easily interpreted by the theory also presented. Data taken on the binary liquid mixture methanol-isooctane are presented and analyzed. The critical temperature and composition were found to be (42.5±0.5) °C and (67.3±0.2)% by volume isooctane, respectively.

  14. Ordering and phase separation of adsorbed binary mixtures

    NASA Astrophysics Data System (ADS)

    Mahale, N. K.; Cole, M. W.

    1986-10-01

    The ground state energy is calculated for mixtures adsorbed on graphite and Ag surfaces. The graphite case considers noble gases adsorbed in a commensurate array, while for Ag the substrate is ignored except for its mediation of the interatomic interaction. The balance between alternative possible structures is sensitive to the assumed interaction, for which realistic potential models are employed. Comparison is made with predictions based on simple combining rules. The cases of Ar mixtures with N 2 or CO on graphite are treated, including both herringbone and pinwheel structures for the N 2. Finite temperature behavior is described qualitatively.

  15. Synergistic effects and correlating polarity parameters in binary mixtures of ionic liquids.

    PubMed

    Beniwal, Vijay; Kumar, Anil

    2015-04-07

    Understanding how a chemical reaction proceeds in solution requires precise knowledge of solute-solvent interactions. Certain issues involved in ionic liquid binary mixtures are still not clearly understood, including: 1) the effects of hydrogen-bond-acceptor basicity (β) of solvents on the "synergistic effects" found in ionic liquid-alcohol mixtures, 2) the interrelation between the polarity parameters in binary mixtures, and 3) the application of a model for the description of normalised electronic transition energy for all the binary mixtures. Here, a detailed analysis of polarity parameters in both hydrophilic and hydrophobic ionic liquids has been carried out. A three-parameter model developed by Roses et al. [J. Chem. Soc. Perkin Trans. 2 1997, 1341-1348] was found to be applicable to all the binary mixtures, and synergistic effects are generated as a result of high β values of alcohols compared with those of the ionic liquids. A strong correlation was observed in the β values and hydrophobicities of pure ionic liquids, suggesting that β values can play a role in describing synergism.

  16. Bactericidal action of binary and ternary mixtures of carvacrol, thymol, and eugenol against Listeria innocua.

    PubMed

    García-García, Rebeca; López-Malo, Aurelio; Palou, Enrique

    2011-03-01

    The bactericidal effect of 3 natural agents (carvacrol, thymol, and eugenol) was evaluated as well as their binary and ternary mixtures on Listeria innocua inactivation in liquid model systems. Minimal bactericidal concentrations (MBC) of these agents were determined, and then binary and ternary mixtures were evaluated. Culture media were inoculated with L. innocua and incubated for 72 h at 35 °C. Turbidity of studied systems were determined every 24 h. The most effective individual antimicrobial agent was carvacrol, followed by thymol and then eugenol with MBCs of 150, 250, and 450 mg kg(-1), respectively. It was observed that the most effective binary mixture was 75 mg kg(-1) carvacrol and 62.5 mg kg(-1) thymol. Furthermore, the ternary mixture carvacrol-thymol-eugenol in concentrations of 75, 31.25, and 56.25 mg kg(-1), correspondingly, was the most effective for L. innocua inactivation. Several binary and ternary mixtures of these 3 natural antimicrobial agents worked adequately to inactivate L. innocua.

  17. Hydrogen-component fugacity coefficients in binary mixtures with isobutane: temperature dependence

    NASA Astrophysics Data System (ADS)

    Bruno, T. J.; Outcalt, S. L.

    1990-01-01

    The fugacity coefficients of hydrogen in binary mixtures with isobutane were measured using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane through which hydrogen, but not isobutane, can penetrate. Measurement of the gas pressures inside and outside the membrane allow a direct measurement of the hydrogen component fugacity at a given temperature, binary mixture mole fraction, and mixture pressure. In this paper, results are reported at 120, 140, 160, and 180°C. In each case, the total pressure of the mixture was maintained at an average value of 3.40 MPa. The general qualitative features of the data are discussed, and comparisions are made with predictions obtained from the Redlich-Kwong and the Peng-Robinson equations of state.

  18. Sub-shock formation in Grad 10-moment equations for a binary gas mixture

    NASA Astrophysics Data System (ADS)

    Bisi, Marzia; Conforto, Fiammetta; Martalò, Giorgio

    2016-09-01

    The shock structure problem for Grad 10-moment equations for an inert binary mixture is investigated: necessary conditions for the formation of sub-shocks in fields of only one gas or of both components are rigorously obtained, and a detailed comparison with the shock-wave structure of its principal sub-system (deduced assuming vanishing viscous stress tensors) and of the equilibrium Euler sub-system is performed. Some numerical simulations for a mixture of argon and helium are presented.

  19. X-ray specular reflectivity study of a critical binary fluid mixture.

    PubMed

    Marschand, L W; Brown, M; Lurio, L B; Law, B M; Uran, S; Kuzmenko, I; Gog, T

    2005-07-01

    We have used direct inversion of x-ray reflectivity data to extract the liquid-vapor interface composition profile and the related critical scaling function of a binary mixture of dodecane and tetrabromoethane. The mixture was in the one-phase region above its critical point. The results indicate the formation of a monolayer of the lower surface tension component followed by an abrupt change to a mixed composition which gradually relaxes to the bulk composition deep within the fluid.

  20. Excess molar enthalpies of binary mixtures containing mono- and polybromoalkanes at 298.15 K

    SciTech Connect

    Blanco, S.T.; Munoz, J.; Velasco, I.; Otin, S.

    1995-05-01

    An isobaric and quasi-isothermic calorimeter has been used to determine excess molar enthalpies, H{sub m}{sup E}, at 298.15 K and atmospheric pressure for 10 binary mixtures containing dibromomethane, tribromomethane, 1,2-dibromoethane, 1,1,2,2-tetrabromoethane, and 1-bromopropane. H{sub m}{sup E} values for these mixtures are negative except for 1,2-dibromoethane or dibromomethane + 1-bromopropane and 1,1,2,2-tetrabromoethane + tribromomethane.

  1. Excess heat capacity in liquid binary alkali-fluoride mixtures.

    PubMed

    Beilmann, M; Beneš, O; Capelli, E; Reuscher, V; Konings, R J M; Fanghänel, Th

    2013-03-04

    Using drop calorimetry, we measured enthalpy increments of the LiF-KF, LiF-RbF, and LiF-CsF binary systems at temperatures above the melting point. Ten samples with different compositions (four compositions for LiF-KF, one composition for LiF-RbF, and five compositions for LiF-CsF) were prepared and measured between 884 K and 1382 K. To protect the calorimeter from corrosive fluoride vapor at high temperature, an encapsulating technique developed for this purpose was used. The samples were filled in nickel containers that were sealed by laser welding and afterward used for the measurements. From the obtained results, we derived the molar heat capacity functions of the respective samples. The heat capacities of the samples, having different compositions of the same binary system, were compared with the values for ideal behavior and the excess heat capacity function was determined for the entire composition range of the liquid solution. It was found that the excess heat capacities clearly depend on the cation radius and increase in the following order: LiF-NaF < LiF-KF < LiF-RbF < LiF-CsF.

  2. Wetting of a symmetrical binary fluid mixture on a wall.

    PubMed

    Schmid, F; Wilding, N B

    2001-03-01

    We study the wetting behavior of a symmetrical binary fluid below the demixing temperature at a nonselective attractive wall. Although it demixes in the bulk, a sufficiently thin liquid film remains mixed. On approaching liquid vapor coexistence, however, the thickness of the liquid film increases and it may demix and then wet the substrate. We show that the wetting properties are determined by an interplay of the two length scales related to the density and the composition fluctuations. The problem is analyzed within the framework of a generic two component Ginzburg-Landau functional (appropriate for systems with short-ranged interactions). This functional is minimized both numerically and analytically within a piecewise parabolic potential approximation. A number of surface transitions are found, including first-order demixing and prewetting, continuous demixing, a tricritical point connecting the two regimes, or a critical end point beyond which the prewetting line separates a strongly and a weakly demixed film. Our results are supported by detailed Monte Carlo simulations of a symmetrical binary Lennard-Jones fluid at an attractive wall.

  3. Benard convection in binary mixtures with Soret effects and solidification

    NASA Technical Reports Server (NTRS)

    Zimmermann, G.; Mueller, U.; Davis, S. H.

    1992-01-01

    Benard convection was studied in a two-component liquid which displayed Soret effects (Soret, 1879; DeGroot and Mazur, 1969) and in which the temperatures of the horizontal boundaries spanned the solidification temperature of the mixture. A steady basic state was observed, in which the layer is partly liquid (near the lower, heated plate) and partly solid (near the upper, cooled plate) with the interface being planar, and in which all transport is by conduction and diffusion. Linear stability of the basic state was examined to determine how the presence of solid and the ability of the material to solidify or melt under disturbance affects the critical conditions from the onset of instability. The theoretical results obtained for cases when the phase change is absent and when the Soret effects are absent (but the phase change is present) are compared with an experiment using alcohol-water mixtures.

  4. Demixing in binary mixtures of apolar and dipolar hard spheres.

    PubMed

    Almarza, N G; Lomba, E; Martín, C; Gallardo, A

    2008-12-21

    We study the demixing transition of mixtures of equal size hard spheres and dipolar hard spheres using computer simulation and integral equation theories. Calculations are carried out at constant pressure, and it is found that there is a strong correlation between the total density and the composition. The critical temperature and the critical total density are found to increase with pressure. The critical mole fraction of the dipolar component on the contrary decreases as pressure is augmented. These qualitative trends are reproduced by the theoretical approaches that on the other hand overestimate by far the value of the critical temperature. Interestingly, the critical parameters for the liquid-vapor equilibrium extrapolated from the mixture results in the limit of vanishing neutral hard sphere concentration agree rather well with recent estimates based on the extrapolation of charged hard dumbbell phase equilibria when dumbbell elongation shrinks to zero [G. Ganzenmuller and P. J. Camp, J. Chem. Phys. 126, 191104 (2007)].

  5. Benard convection in binary mixtures with Soret effects and solidification

    NASA Astrophysics Data System (ADS)

    Zimmermann, G.; Mueller, U.; Davis, S. H.

    1992-05-01

    Benard convection was studied in a two-component liquid which displayed Soret effects (Soret, 1879; DeGroot and Mazur, 1969) and in which the temperatures of the horizontal boundaries spanned the solidification temperature of the mixture. A steady basic state was observed, in which the layer is partly liquid (near the lower, heated plate) and partly solid (near the upper, cooled plate) with the interface being planar, and in which all transport is by conduction and diffusion. Linear stability of the basic state was examined to determine how the presence of solid and the ability of the material to solidify or melt under disturbance affects the critical conditions from the onset of instability. The theoretical results obtained for cases when the phase change is absent and when the Soret effects are absent (but the phase change is present) are compared with an experiment using alcohol-water mixtures.

  6. Benard convection in binary mixtures with Soret effects and solidification

    NASA Technical Reports Server (NTRS)

    Zimmermann, G.; Mueller, U.; Davis, S. H.

    1992-01-01

    Benard convection was studied in a two-component liquid which displayed Soret effects (Soret, 1879; DeGroot and Mazur, 1969) and in which the temperatures of the horizontal boundaries spanned the solidification temperature of the mixture. A steady basic state was observed, in which the layer is partly liquid (near the lower, heated plate) and partly solid (near the upper, cooled plate) with the interface being planar, and in which all transport is by conduction and diffusion. Linear stability of the basic state was examined to determine how the presence of solid and the ability of the material to solidify or melt under disturbance affects the critical conditions from the onset of instability. The theoretical results obtained for cases when the phase change is absent and when the Soret effects are absent (but the phase change is present) are compared with an experiment using alcohol-water mixtures.

  7. Surface freezing in binary alkane-alcohol mixtures

    SciTech Connect

    Ofer, E.; Sloutskin, E.; Tamam, L.; Deutsch, M.; Ocko, B. M.

    2006-08-15

    Surface freezing was detected and studied in mixtures of alcohol and alkane molecules, using surface tensiometry and surface-specific x-ray scattering methods. Considering that surface freezing in pure alkanes forms an ordered monolayer and in alcohols it forms an ordered bilayer, the length mismatch repulsion was minimized by varying the carbon number of the alkane component around 2n, where n is the carbon number of the alcohol molecule. A solutionlike behavior was found for all mixtures, where the ideal liquid mixture phase-separates upon freezing both in the bulk and the surface. The solid exhibits a herringbone crystalline phase below an alkane mole fraction {phi}{sub t}{approx_equal}0.8 and a rotator phase above it. The surface frozen film below {phi}{sub t} is an alkane monolayer exhibiting a next-nearest neighbor molecular tilt of a composition-dependent magnitude. Above {phi}{sub t}, no diffraction peaks were observed. This could be explained by the intrinsically shorter-range order of the rotator phase and a possible proliferation of defects.

  8. Percolating ion transport in binary mixtures with high dielectric loss

    NASA Astrophysics Data System (ADS)

    Brohede, U.; Strømme, M.

    2006-05-01

    We investigate the ion transport percolation properties of a binary system of an ion conductor (NaCl) and an insulator (ethyl cellulose) for which the ac component of the conductivity is non-negligible over the entire measured frequency range. We find that the dc conductivity, extracted from a well-defined range of frequencies, can be described by a low percolation threshold, ϕc=0.06 three-dimensional conducting network. The low ϕc was explained by the water-layer-assisted ion conduction in micrometer-sized ethyl cellulose channels between NaCl grains. The present findings provide valuable knowledge for the analysis and design of a broad class of ion conducting functional materials.

  9. Study of structural and transport properties of argon, krypton, and their binary mixtures at different temperatures.

    PubMed

    Ghimire, Sunil; Adhikari, Narayan Prasad

    2017-03-01

    Molecular dynamics simulation of argon, krypton, and their binary mixtures were performed at different temperatures and constant pressure (P = 1.013 bar) using GROMACS - Groningen Machine for Chemical Simulations. The gases are modeled by Lennard-Jones pair potential, with parameters taken from the literature. The study of radial distribution functions (RDFs) shows a single peak which indicates that there is no packing effect in gaseous state for argon, krypton, and their binary mixtures. The self-diffusion coefficients of argon and krypton is determined by using mean-square displacement(MSD) method and the mutual diffusion coefficients of binary mixtures are determined using Darken's relation. The values of simulated diffusion coefficients are compared with their corresponding theoretical values, numerical estimation, and experimental data. A good agreement between these sets of data is found. The diffusion coefficients obey Arrhenius behavior to a good extent for both pure components and binary mixtures. The values of simulated diffusion coefficient are used to estimate viscosities and thermal conductivities which agree with theoretical values, numerical estimation, and experimental data within 10 %. These results support that the LJ potential is sufficient for description of molecular interactions in argon and krypton.

  10. Boundary integral approach for propagating interfaces in a binary non-isothermal mixture

    NASA Astrophysics Data System (ADS)

    Alexandrov, D. V.; Galenko, P. K.

    2017-03-01

    A method based on boundary integral approach to the propagation of curved phase interface in a binary non-isothermal mixture is developed. Previously known equations and solutions for thermally controlled growth and needle-like dendrites follow from the obtained boundary integral equations as limiting cases.

  11. Binary mixtures of ionic liquids: a joint approach to investigate their properties and catalytic ability.

    PubMed

    D'Anna, Francesca; Marullo, Salvatore; Vitale, Paola; Noto, Renato

    2012-05-14

    The growing interest in the properties and applications of ionic liquids has recently led to research into the possibility of using their binary mixtures. This work reports on the effects of binary mixtures of ionic liquids on the outcome of organic reactions such as the mononuclear rearrangement of heterocycles and the solvatochromic behavior of Nile Red. Binary mixtures formed by ionic liquids differing in the structure of the cation and the anion are taken into account. In particular, ionic liquids such as 1-benzyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide, 1-(2,3,4,5,6-pentafluorobenzyl)-3-butylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-benzyl-3-butylimidazolium tetrafluoroborate, are studied. To achieve a deep understanding of the properties of ionic-liquid binary mixtures, their three-dimensional organization was analyzed by a combination of resonance light scattering, UV/Vis spectroscopy, and (1)H and (19)F NMR spectroscopy. Data collected herein evidence that the most significant changes in the ionic lattice structure, and consequently the most pronounced effects exerted as solvent media, occur when the studied system involves a blend of different anions.

  12. Binary Mixtures of Permanganate and Chlorinated Volatile Organic Compounds in Groundwater Samples: Sample Preservation and Analysis

    EPA Science Inventory

    Ground water samples collected at sites where in-situ chemical oxidation (ISCO) has been deployed may contain binary mixtures of ground water contaminants and permanganate (MnO4-), an oxidant injected into the subsurface to destroy the contaminant. Commingling of the oxidant and ...

  13. Combining nitrogen fertilizer with poultry litter in a binary mixture of tall fescue and bermudagrass

    USDA-ARS?s Scientific Manuscript database

    A common problem when poultry litter is applied to pastures in the southeastern USA is the buildup of soil P because of the difference in N-P-K ratio of the litter and plant requirements. This 2-yr study tested the theory that if the N requirement of a tall fescue-bermudagrass binary mixture is only...

  14. Seasonal nitrogen effects on nutritive value in binary mixtures of tall fescue and bermudagrass

    USDA-ARS?s Scientific Manuscript database

    Year-round forage production is feasible in much of the southeastern USA through utilization of cool- and warm-season forages. This study determined changes in herbage nutritive value in binary mixtures of cool-season, tall fescue [Schedonorus arundinaceus (Schreb.) Dumort], and warm-season, bermuda...

  15. Binary Mixtures of Permanganate and Chlorinated Volatile Organic Compounds in Groundwater Samples: Sample Preservation and Analysis

    EPA Science Inventory

    Ground water samples collected at sites where in-situ chemical oxidation (ISCO) has been deployed may contain binary mixtures of ground water contaminants and permanganate (MnO4-), an oxidant injected into the subsurface to destroy the contaminant. Commingling of the oxidant and ...

  16. NEUROBEHAVIORAL EVALUATIONS OF BINARY AND TERTIARY MIXTURES OF CHEMICALS: LESSIONS LEARNING.

    EPA Science Inventory

    The classical approach to the statistical analysis of binary chemical mixtures is to construct full dose-response curves for one compound in the presence of a range of doses of the second compound (isobolographic analyses). For interaction studies using more than two chemicals, ...

  17. Proton-transfer laser. Dual wavelength lasing action in binary dye mixtures involving 3-hydroxyflavone

    SciTech Connect

    Chou, P.; Aartsma, T.J.

    1986-02-27

    Amplified spontaneous emission is observed from 3-hydroxyflavone and from a laser dye simultaneously in a binary mixture. This observation is interpreted in terms of a rapid tautomerization in the 3-hydroxyflavone ground state, minimizing reabsorption between 400 and 500 nm. 8 references, 4 figures, 1 table.

  18. NEUROBEHAVIORAL EVALUATIONS OF BINARY AND TERTIARY MIXTURES OF CHEMICALS: LESSIONS LEARNING.

    EPA Science Inventory

    The classical approach to the statistical analysis of binary chemical mixtures is to construct full dose-response curves for one compound in the presence of a range of doses of the second compound (isobolographic analyses). For interaction studies using more than two chemicals, ...

  19. Establishment and yield of perennial grass monocultures and binary mixtures for bioenergy in North Dakota

    USDA-ARS?s Scientific Manuscript database

    To develop appropriate bioenergy production systems to match site-specific situations, establishment and yield were evaluated for switchgrass, intermediate wheatgrass, tall wheatgrass, and three binary mixtures at four sites in North Dakota from 2006 to 2011. Canopy cover at harvest for intermediat...

  20. Cultivar x binary mixture interaction effect on agronomic traits in orchardgrass

    USDA-ARS?s Scientific Manuscript database

    A study was conducted to evaluate and characterize the agronomic value, including dry matter yield and forage quality of 25 orchardgrass cultivars grown in monoculture and binary mixtures with alfalfa under supplemental irrigation from 2009 to 2012 at a Millville, UT, field site. Orchardgrass monoc...

  1. Thermal characteristics of oleochemical carbonate binary mixtures for potential latent heat storage

    USDA-ARS?s Scientific Manuscript database

    The present study examines the thermal properties of melting and solidification for binary mixtures between dodecyl carbonate (1a), tetradecyl carbonate (1b), hexadecyl carbonate (1c), and octadecyl carbonate (1d) by differential scanning calorimetry (DSC) in order to gain further understanding of t...

  2. Reverse solvatochromism in solvent binary mixtures: a case study using a 4-(nitrostyryl)phenolate as a probe.

    PubMed

    Stock, Rafaela I; Schramm, Adriana D S; Rezende, Marcos C; Machado, Vanderlei G

    2016-07-27

    A 4-(nitrostyryl)phenolate was synthesized and its use in pure solvents revealed a reversion in solvatochromism. Solutions of a dye in binary solvent mixtures, using as components the solvents in the region of the occurrence of the reversion, provided the first case in the literature of reverse solvatochromism in a binary mixture.

  3. Stokes shift dynamics in (ionic liquid + polar solvent) binary mixtures: composition dependence.

    PubMed

    Daschakraborty, Snehasis; Ranjit, Biswas

    2011-04-14

    An approximate semimolecular theory has been developed to investigate the composition dependence of Stokes shift dynamics of a fluorescent dye molecule dissolved in binary mixtures of an ionic liquid (IL) with a conventional polar solvent at different mole fractions. The theory expresses the dynamic Stokes shift as a sum of contributions from the dye-IL and the dye-polar solvent interactions and suggests substantial solute-cation dipole-dipole interaction contribution to the solvation energy relaxation. The theory, when applied to aqueous mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF(6)]) and tetrafluoroborate ([Bmim][BF(4)]), and binary mixtures of ([Bmim][BF(4)] + acetonitrile), predicts reduction of Stokes shift but acceleration of the dynamics upon increasing the polar solvent concentration for the most part of the mixture composition. The decrease in dynamic Stokes shift values has been found to occur due to decrease of the dye-IL interaction in the presence of the added polar solvent. For aqueous binary mixtures of IL, the predicted results are in semiquantitative agreement with the available experimental results. However, the calculated dynamics suggest much weaker composition dependence than that observed in experiments. In addition, the theory predicts a turn around for dynamic Stokes shift in its composition dependence for ([Bmim][BF(4)] + acetonitrile) mixtures at higher dilutions of the IL. Interestingly, effective dipolar medium calculations for Stokes shift dynamics in ([Bmim][BF(4)] + dichloromethane) binary mixtures predict a very weak or even nonexistent nonlinear composition dependence. These predictions should be reexamined in experiments.

  4. 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.

  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. Toxic effect of metal cation binary mixtures to the seaweed Gracilaria domingensis (Gracilariales, Rhodophyta).

    PubMed

    Mendes, Luiz Fernando; Stevani, Cassius Vinicius; Zambotti-Villela, Leonardo; Yokoya, Nair Sumie; Colepicolo, Pio

    2014-01-01

    The macroalga Gracilaria domingensis is an important resource for the food, pharmaceutical, cosmetic, and biotechnology industries. G. domingensis is at a part of the food web foundation, providing nutrients and microelements to upper levels. As seaweed storage metals in the vacuoles, they are considered the main vectors to magnify these toxic elements. This work describes the evaluation of the toxicity of binary mixtures of available metal cations based on the growth rates of G. domingensis over a 48-h exposure. The interactive effects of each binary mixture were determined using a toxic unit (TU) concept that was the sum of the relative contribution of each toxicant and calculated using the ratio between the toxicant concentration and its endpoint. Mixtures of Cd(II)/Cu(II) and Zn(II)/Ca(II) demonstrated to be additive; Cu(II)/Zn(II), Cu(II)/Mg(II), Cu(II)/Ca(II), Zn(II)/Mg(II), and Ca(II)/Mg(II) mixtures were synergistic, and all interactions studied with Cd(II) were antagonistic. Hypotheses that explain the toxicity of binary mixtures at the molecular level are also suggested. These results represent the first effort to characterize the combined effect of available metal cations, based on the TU concept on seaweed in a total controlled medium. The results presented here are invaluable to the understanding of seaweed metal cation toxicity in the marine environment, the mechanism of toxicity action and how the tolerance of the organism.

  7. 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.

  8. Controlled structuring of binary hard-disk mixtures via a periodic, external potential.

    PubMed

    Franzrahe, K; Nielaba, P

    2009-05-01

    Ordering phenomena on surfaces or in monolayers can be successfully studied by model systems as binary hard-disk mixtures, the influence of a substrate being modeled by an external potential. For the field-free case the thermodynamic stability of space-filling lattice structures for binary hard-disk mixtures is studied by Monte Carlo computer simulations. As these structures prove to be thermodynamically stable only in high pressure environments, the phase behavior of an equimolar binary mixture with a diameter ratio of sigma_{B}/sigma_{A}=0.414 exposed to an external, one-dimensional, periodic potential is analyzed in detail. The underlying ordering mechanisms and the resulting order differ considerably, depending on which components of the mixture interact with the external potential. The simulations show that slight deviations in the concentration of large particles x_{A} or the diameter ratio sigma_{B}/sigma_{A} have no impact on the occurrence of the various field-induced phenomena as long as the mixture stays in the relevant regime of the packing fraction eta . Furthermore the importance of the commensurability of the external potential to the S1(AB) square lattice for the occurrence of the induced ordering is discussed.

  9. Dynamics of binary phase separation in liquid He-3-He-4 mixtures

    NASA Technical Reports Server (NTRS)

    Hoffer, J. K.; Sinha, D. N.

    1986-01-01

    Binary phase-separation dynamics in liquid mixtures of He-3 and He-4 has been investigated near the tricritical point with laser-light scattering techniques. Rapid decompression of the mixtures results in quenches into the miscibility gap so that both the metastable and unstable (spinodal) regions can be probed. Quenches into the unstable region allowed measurements of the normalized dynamic structure factor S(k,t) that confirm the dynamical scaling hypotheses for spinodal decomposition. Measurements made for concentrations well away from the tricritical value show different behavior and suggest the presence of a spinodal boundary. Forward scattering intensities for shallow quenches probe nucleation phenomena and permit quantitative measurements of anomalous super-cooling as a function of quench rate. Comparisons with data in organic binary mixtures are given.

  10. Dissipative dynamics of the Josephson effect in binary Bose-Einstein-condensed mixtures

    NASA Astrophysics Data System (ADS)

    Burmistrov, S. N.

    2011-06-01

    The dissipative dynamics of a pointlike Josephson junction in binary Bose-Einstein-condensed mixtures is analyzed within the framework of the model of a tunneling Hamiltonian. The transmission of unlike particles across a junction is described by the different transmission amplitudes. The effective action that describes the dynamics of the phase differences across the junction for each of two condensed components is derived by employing the functional integration method. In the low-frequency limit the dynamics of a Josephson junction can be described by two coupled equations in terms of the potential energy and dissipative Rayleigh function using a mechanical analogy. The interplay between mass currents of each mixture component appears in the second-order term in the tunneling amplitudes due to the interspecies hybridizing interaction. The asymmetric case of the binary mixtures with different concentrations and order parameters is considered as well.

  11. Size Segregation of Binary Granular Mixtures - Towards more appropriate scaling of percolation velocity

    NASA Astrophysics Data System (ADS)

    Tripathi, Anurag; Nema, Mohit

    2017-06-01

    We study size segregation of binary granular mixtures flowing over an inclined plane using DEM simulations. We critically examine the recently proposed scaling of the species percolation velocity with the local shear rate for different inclination angles and size ratios for an equal volume mixture of large and small spherical particles. Our DEM simulations explore a much wider range of inclination angles and shear rates for three different size ratios of large and small particles. Our results suggest that while the scaling of percolation velocity with the shear rate seems to work well for any given inclination angle, this scaling is unable to capture the influence of inclination angle on the segregation. We overcome this limitation and propose a more appropriate way of scaling the percolation velocity. This scaling, when used along with the convection-diffusion equation, is able to predict the steady state segregation of binary mixtures flowing at different inclination angles for different size ratios.

  12. Critical Lines in Binary Mixtures of Components with Multiple Critical Points

    NASA Astrophysics Data System (ADS)

    Artemenko, Sergey; Lozovsky, Taras; Mazur, Victor

    The principal aim of this work is a comprehensive analysis of the fluid phase behavior of binary fluid mixtures via the van der Waals like equation of state (EoS) which has a multiplicity of critical points in metastable region. We test the modified van der Waals equation of state (MVDW) proposed by Skibinski et al. (2004) which displays a complex phase behavior including three critical points and identifies four fluid phases (gas, low density liquid (LDL), high density liquid (HDL), and very high density liquid (VHDL)). An improvement of repulsive part doesn't change a topological picture of phase behavior in the wide range of thermodynamic variables. The van der Waals attractive interaction and excluded volume for mixture are calculated from classical mixing rules. Critical lines in binary mixtures of type III of phase behavior in which the components exhibit polyamorphism are calculated and a continuity of fluid-fluid critical line at high pressure is observed.

  13. Bubble and droplet motion in binary mixtures: Evaporation-condensation mechanism and Marangoni effect.

    PubMed

    Onuki, Akira

    2009-04-01

    Bubble and droplet motion in binary mixtures is studied in weak heat and diffusion fluxes and in gravity by solving the linearized hydrodynamic equations supplemented with appropriate surface boundary conditions. Without gravity, the velocity field is induced by evaporation and condensation at the interface and by the Marangoni effect due to a surface-tension gradient. In pure fluids, the latter nearly vanishes since the interface temperature tends to the coexistence temperature T_{cx}(p) even in heat flow. In binary mixtures, the velocity field can be much enhanced by the Marangoni effect above a crossover concentration c;{ *} inversely proportional to the radius R of the bubble or droplet. Here c;{ *} is usually very small for large R for non-azeotropic mixtures. The temperature and concentration deviations are also calculated.

  14. Experience influences elemental and configural perception of certain binary odour mixtures in newborn rabbits.

    PubMed

    Sinding, Charlotte; Thomas-Danguin, Thierry; Crepeaux, Guillemette; Schaal, Benoist; Coureaud, Gérard

    2011-12-15

    Elemental and configural olfactory perception allows interaction with the environment from very early in life. To evaluate how newborn rabbits can extract and respond to information from the highly complex chemical surroundings, and how experience acts on this sensory, cognitive and behavioural capability, we ran a study in four steps including a total of eight experiments. We mainly used a binary AB mixture comprising ethyl isobutyrate (component A) and ethyl maltol (component B), previously shown as a bearer of blending properties; in rabbit pups (as in human adults), the mixture elicits a weak configural perception, i.e. the perception of a configural odour different from the odours of the components. First, a repeated exposure to one component of AB led to a more elemental perception of this mixture; conversely, a repeated exposure to AB facilitated its configural processing. Second, similar impact of experience did not appear with a non-blending AC mixture (ethyl isobutyrate-guaïacol). Third, repeated exposure to AB impacted not only the perception of AB, but also and in the same way the perception of the AC mixture sharing one component, and reciprocally. However, facilitation to perceive one mixture in one mode (configural/elemental) was not generalized to a mixture sharing no components with the experienced mixture [AB versus DE (damascenone and vanillin)]. Thus, experience contributes to the neonatal perception of odour mixtures and adds plasticity to the perceptual system. However, this impact remains dependent on the chemical composition of the mixtures.

  15. A combined ultrasonic flow meter and binary vapour mixture analyzer for the ATLAS silicon tracker

    NASA Astrophysics Data System (ADS)

    Bates, R.; Battistin, M.; Berry, S.; Berthoud, J.; Bitadze, A.; Bonneau, P.; Botelho-Direito, J.; Bousson, N.; Boyd, G.; Bozza, G.; Da Riva, E.; Degeorge, C.; Deterre, C.; DiGirolamo, B.; Doubek, M.; Giugni, D.; Godlewski, J.; Hallewell, G.; Katunin, S.; Lombard, D.; Mathieu, M.; McMahon, S.; Nagai, K.; Perez-Rodriguez, E.; Rossi, C.; Rozanov, A.; Vacek, V.; Vitek, M.; Zwalinski, L.

    2013-02-01

    We describe a combined ultrasonic instrument for gas flow metering and continuous real-time binary gas composition measurements. The combined flow measurement and mixture analysis algorithm employs sound velocity measurements in two directions in combination with measurements of the pressure and temperature of the process gas mixture. The instrument has been developed in two geometries following extensive computational fluid dynamics studies of various mechanical layouts. A version with an axial sound path has been used with binary gas flows up to 230 l.min-1, while a version with a sound path angled at 45° to the gas flow direction has been developed for use in gas flows up to 20000 l.min-1. The instrument with the axial geometry has demonstrated a flow resolution of <= 1 % of full scale for flows up to 230 l.min-1 and a mixture resolution of 3.10-3 for C3F8/C2F6 molar mixtures with ~ 20 %C2F6. Higher mixture precision is possible in mixtures of gases with widely-differing molecular weight (mw): a sensitivity of < 5.10-5 to traces of C3F8 in nitrogen (mw difference 160) has been seen in a long duration ( > 1yr) continuous study. A prototype instrument with 45° crossing angle has demonstrated a flow resolution of 1.9 % of full scale for linear flow velocities up to 15 ms-1. Although this development was motivated by a requirement of the ATLAS silicon tracker evaporative fluorocarbon cooling system, the developed instrument can be used in many applications where continuous knowledge of binary gas composition is required. Applications include the analysis of hydrocarbons, vapour mixtures for semi-conductor manufacture and anaesthetic gas mixtures.

  16. Linear mixing rule in screened binary ionic mixtures

    NASA Technical Reports Server (NTRS)

    Chabrier, G.; Ashcroft, N. W.

    1990-01-01

    The validity of the linear mixing rule is examined for the following two cases (1) when the response of the electron gas is taken into account in the effective ionic interaction and (2) when finite-temperature effects are included in the dielectric response of the electrons, i.e., when the ions interact with both temperature- and density-dependent screened Coulomb potentials. It is found that the linear mixing rule remains valid when the electron response is taken into account in the interionic potential at any density, even though the departure from linearity can reach a few percent for the asymmetric mixtures in the region of weak degeneracy for the electron gas. A physical explanation of this behavior is proposed which is based on a simple additional length scale.

  17. Characterizing Olfactory Binary Mixture Interactions in Fischer 344 Rats Using Behavioral Reaction Times

    PubMed Central

    Yoder, Wendy M.; Gaynor, Leslie; Windham, Ethan; Lyman, Michelle; Munizza, Olivia; Setlow, Barry; Bizon, Jennifer L.

    2015-01-01

    Response times provide essential subthreshold perceptual data that extend beyond accuracy alone. Behavioral reaction times (RTs) were used to characterize rats’ ability to detect individual odorants in a series of complimentary binary odorant mixture ratios. We employed an automated, liquid-dilution olfactometer to train Fischer 344 rats (N = 8) on an odor identification task using nonreinforced probe trials. Binary mixture ratios composed of aliphatic odorants (citral and octanol) were arranged such that relative contributions of the 2 components varied systematically by a factor of 1% (v/v). Odorant concentrations for the target (S+), control (S−), and mixture (S+:S−) odorants were presented relative to threshold for each rat. Rats were initially trained to respond by licking at a spout to obtain liquid reward for either citral or octanol as the reinforced target (S+) odorant. After achieving 100% accuracy, rats were transferred to variable ratio (VR 2) reinforcement for correct responding. Nonreinforced probe trials (2 per block of 22 trials) were tested for each mixture ratio and recorded as either S+ (rats lick-responded in the presence of the mixture) or S− (rats refrained from licking), thereby indicating detection of the trained, S+ odorant. To determine the perceived salience for each ratio, RTs (latency from odorant onset to lick response) were recorded for each trial. Consistent with previous studies, RTs for both odorants were shortest (~150–200ms) when the probe trials consisted of a single, monomolecular component. Binary mixtures that contained as little as 1% of the S−, nontarget odorant, however, were sufficiently different perceptually to increase behavioral RTs (i.e., rats hesitated longer before responding); RTs changed systematically as a function of the binary ratio. Interestingly, the rate of RT change was dependent on which odorant served as the S+, suggesting an asymmetric interaction between the 2 odorants. The data demonstrate

  18. 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.

  19. Dynamic scaling of the critical binary mixture methanol-hexane.

    PubMed

    Iwanowski, I; Sattarow, A; Behrends, R; Mirzaev, S Z; Kaatze, U

    2006-04-14

    Acoustical attenuation spectrometry, dynamic light scattering, shear viscosity, density, and heat capacity measurements of the methanol/n-hexane mixture of critical composition have been performed. The critical part in the sonic attenuation coefficients nicely fits to the empirical scaling function of the Bhattacharjee-Ferrell [Phys. Rev. A 24, 1643 (1981)] dynamic scaling model if the theoretically predicted scaled half-attenuation frequency Omega(12) (BF)=2.1 is used. The relaxation rates of order parameter fluctuations, as resulting from the acoustical spectra, within the limits of experimental error agree with those from a combined evaluation of the light scattering and shear viscosity measurements. Both series of data display power law with amplitude Gamma(0)=44x10(9) s(-1). The amplitude of the fluctuation correlation length follows as xi(0)=0.33 nm from the light scattering data and as xi(0)=0.32 nm from the amplitude of the singular part of the heat capacity if the two-scale factor universality relation is used. The adiabatic coupling constant g=0.11 results from the amplitude of the critical contribution to the acoustical spectrum near the critical point, in conformity with g=0.12 as following from the variation of the critical temperature with pressure along the critical line and the thermal expansion coefficient.

  20. Mechanisms in the size segregation of a binary granular mixture

    NASA Astrophysics Data System (ADS)

    Schröter, Matthias; Ulrich, Stephan; Kreft, Jennifer; Swift, Jack B.; Swinney, Harry L.

    2006-07-01

    A granular mixture of particles of two sizes that is shaken vertically will in most cases segregate. If the larger particles accumulate at the top of the sample, this is called the Brazil-nut effect (BNE); if they accumulate at the bottom, it is called the reverse Brazil-nut effect (RBNE). While this process is of great industrial importance in the handling of bulk solids, it is not well understood. In recent years ten different mechanisms have been suggested to explain when each type of segregation is observed. However, the dependence of the mechanisms on driving conditions and material parameters and hence their relative importance is largely unknown. In this paper we present experiments and simulations where both types of particles are made from the same material and shaken under low air pressure, which reduces the number of mechanisms to be considered to seven. We observe both BNE and RBNE by varying systematically the driving frequency and amplitude, diameter ratio, ratio of total volume of small to large particles, and overall sample volume. All our results can be explained by a combination of three mechanisms: a geometrical mechanism called void filling, transport of particles in sidewall-driven convection rolls, and thermal diffusion, a mechanism predicted by kinetic theory.

  1. 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.

  2. Nanostructural organization and anion effects in the optical Kerr effect spectra of binary ionic liquid mixtures.

    PubMed

    Xiao, Dong; Rajian, Justin Rajesh; Hines, Larry G; Li, Shengfu; Bartsch, Richard A; Quitevis, Edward L

    2008-10-23

    This article reports a study of the effect of anions on the optical Kerr effect (OKE) spectra of binary ionic liquid mixtures with one mixture comprising the 3-methyl-1-pentylimidazolium ([C 5mim] (+)) cation and the anions PF 6 (-) and CF 3CO 2 (-) (TFA (-)), and another mixture comprising the [C 5mim] (+) cation and the anions Br (-) and bis(trifluomethanesulfonyl)imide (NTf 2 (-)). The spectra were obtained by the use of optical heterodyne-detected Raman-induced Kerr Effect Spectroscopy at 295 K. The OKE spectra of the mixtures are compared with the calculated mole-fraction weighted sum of the normalized OKE spectra of the neat liquids. The OKE spectra are nearly additive for [C 5mim]Br/[C 5mim][NTf 2] mixtures, but nonadditive for [C 5mim][PF 6]/[C 5mim][TFA] mixtures. In the case of the equimolar [C 5mim][PF 6]/[C 5mim][TFA] mixture, the nonadditivity is such that the experimental OKE spectrum is narrower than the calculated OKE spectrum. The additivity or nonadditivity of OKE spectra for IL mixtures can be explained by assuming ionic liquids are nanostructurally organized into nonpolar regions and ionic networks. The ionic networks in mixtures will be characterized by "random co-networks" for anions that are nearly the same in size (PF 6 (-) and TFA (-)) and by "block co-networks" for anions that differ greatly in size (Br (-) and NTf 2 (-)).

  3. Mutagenic potential of binary mixtures of nitro-polychlorinated dibenzo-p-dioxins and related compounds

    SciTech Connect

    Donnelly, K.C.; Brown, K.W.; Estiri, M.; Jones, D.H.; Safe, S.

    1988-01-01

    The mutagenic potential of binary mixtures of nitro-polychlorinated dibenzo-p-dioxins and other environmentally related compounds was determined using Salmonella typhimurium strain TA98 in the standard plate incorporation assay. Samples tested included binary mixtures of 4-nitro-4'-chlorobiphenyl with 6-nitro-4,2',3',4',5'-pentachlorobiphenyl, 4-nitrobenzo-p-dioxin with 4-nitro-2,3,8-trichlorodibenzo-p-dioxin, and benzo(a)pyrene with either nitropentachlorobiphenyl or nitrotrichlorodibenzo-p-dioxin. Inhibition was the primary interaction observed for the mixtures of polyhalogenated dioxins or biphenyls with the direct-acting mutagens nitrodibenzo-p-dioxin or nitrochlorobiphenyl. At the highest dose tested, nitrotrichlorodibenzo-p-dioxin inhibited the bacterial mutagenicity of nitrodibenzo-p-dioxin by almost 50%, while pentachlorobiphenyl inhibited the mutagenicity of nitrobiphenyl by 34%. Conversely, synergism was the primary interaction observed for mixtures of halogenated aromatics with the promutagen benzo(a)pyrene. The addition of nitrotrichlorodioxin to benzo(a)pyrene enhanced the mutagenicity of the latter compound by as much as 70%, while the mutagenic potential of a mixture of benzo(a)pyrene and nitropentachlorobiphenyl was approximately 50% greater than the mutagenicity of benzo(a)pyrene alone. In summary, mixtures of nonmutagenic nitropolyhalogenated biphenyls or dibenzo-p-dioxins appear to inhibit the mutagenicity of direct-acting mutagens, while these same compounds seem to enhance the mutagenic potential of the promutagen benzo(a)pyrene.

  4. The structure of variable property, compressible mixing layers in binary gas mixtures

    NASA Technical Reports Server (NTRS)

    Kozusko, F.; Grosch, C. E.; Jackson, T. L.; Kennedy, Christipher A.; Gatski, Thomas B.

    1996-01-01

    We present the results of a study of the structure of a parallel compressible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H2), helium (He), nitrogen (N2), oxygen (02), neon (Ne) and argon (Ar). Profiles of the variation of the Lewis and Prandtl numbers across the mixing layer for all thirty combinations of gases are given. It is shown that the Lewis number can vary by as much as a factor of eight and the Prandtl number by a factor of two across the mixing layer. Thus assuming constant values for the Lewis and Prandtl numbers of a binary gas mixture in the shear layer, as is done in many theoretical studies, is a poor approximation. We also present profiles of the velocity, mass fraction, temperature and density for representative binary gas mixtures at zero and supersonic Mach numbers. We show that the shape of these profiles is strongly dependent on which gases are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream.

  5. Adsorption of binary mixtures of ethane and acetylene on activated carbon

    SciTech Connect

    Lee, T.V.; Huang, J.C.; Rothstein, D.; Madey, R.

    1984-01-01

    Dynamic measurement of the adsorption of binary mixtures of ethane and acetylene (and also of each gas alone) in a helium carrier gas were made on an (Columbia 4LXC 12/28) activated carbon adsorber bed at 25/sup 0/C. The adsorption capacities of the activated carbon for the pure gases and for each component in the mixtures are extracted from the transmission curves by the use of a mass balance equation. Transmission is the ratio of the concentration at the outlet of the adsorber bed to that at the inlet. The adsorption isotherms for pure ethane and acetylene can be presented by a modified Langmuir isotherm known as the Chakravarti-Dhar isotherm at gas concentrations up to at least 4.2 X 19/sup -7/ mol/cm/sup 3/ (viz., 7.8 mmHg). The gas-adsorbate equilibrium composition and the adsorption capacity of each component in the binary mixture of ethane and acetylene are estimated from the corresponding single-component isotherms by applying ideal adsorbed solution theory (IAST). The fact that the estimated values of the adsorption capacities and the gas-adsorbate equilibrium compositions are in good agreement with those extracted from the measurements for the binary mixtures of ethane and acetylene confirms that the ethane-acetylene system forms an ideal adsorbed phase on activated carbon at a pressure of about 7.3 mmHg and a temperature of 25/sup 0/C. 20 references, 4 figures, 4 tables.

  6. Similarity, independence, or interaction for binary mixture effects of nerve toxicants for the nematode Caenorhabditis elegans.

    PubMed

    Svendsen, Claus; Siang, Pia; Lister, Lindsay J; Rice, Annabel; Spurgeon, David J

    2010-05-01

    Intensive agriculture can require the simultaneous use of more than one pesticide, resulting in the presence of mixtures in soils and waters. To assess mixture effects, concentration addition (CA) for similar acting chemicals and independent action (IA) for dissimilar acting chemicals are the most frequently used models. While the mechanistic basis for the selection of CA and IA for a given mixture appears appealing (similar vs dissimilar action), it has not yet been established how similar chemicals need to be in their effect before CA should be viewed as the most appropriate model. Here this is investigated in studies of the toxicity of binary mixtures of five different pesticides from three classes that have the same putative mode of action (neuroexcitation) but different molecular mechanisms in binary mixture tests with the nematode Caenorhabditis elegans. Effects of exposure on nematode survival were limited at the concentrations tested. Data analysis, therefore, focused on reproductive toxicity. Both CA and IA were found to be valid models for prediction of the toxicity of the 10 mixtures, although for seven CA provided a mathematically better fit. Both models could describe the toxicity for four mixtures; however, evidence for interaction was found in the remaining six cases. Where interactions occurred, these could be explained by information on the potential mechanisms of compound toxicokinetics-particularly when mixtures comprised a metabolically activated and a metabolically deactivated chemical and/or cases where the relative potencies of the two tested chemicals differed greatly. It is concluded, therefore, that detailed analysis of toxicokinetics and toxicodynamics can aid further understanding of interactions in mixtures. Copyright (c) 2010 SETAC.

  7. Excited-state proton transfer dynamics of firefly's chromophore D-luciferin in DMSO-water binary mixture.

    PubMed

    Kuchlyan, Jagannath; Banik, Debasis; Roy, Arpita; Kundu, Niloy; Sarkar, Nilmoni

    2014-12-04

    In this article we have investigated intermolecular excited-state proton transfer (ESPT) of firefly's chromophore D-luciferin in DMSO-water binary mixtures using steady-state and time-resolved fluorescence spectroscopy. The unusual behavior of DMSO-water binary mixture as reported by Bagchi et al. (J. Phys. Chem. B 2010, 114, 12875-12882) was also found using D-luciferin as intermolecular ESPT probe. The binary mixture has given evidence of its anomalous nature at low mole fractions of DMSO (below XD = 0.4) in our systematic investigation. Upon excitation of neutral D-luciferin molecule, dual fluorescence emissions (protonated and deprotonated form) are observed in DMSO-water binary mixture. A clear isoemissive point in the time-resolved area normalized emission spectra further indicates two emissive species in the excited state of D-luciferin in DMSO-water binary mixture. DMSO-water binary mixtures of different compositions are fascinating hydrogen bonding systems. Therefore, we have observed unusual changes in the fluorescence emission intensity, fluorescence quantum yield, and fluorescence lifetime of more hydrogen bonding sensitive anionic form of D-luciferin in low DMSO content of DMSO-water binary mixture.

  8. Assessment of combined antiandrogenic effects of binary parabens mixtures in a yeast-based reporter assay.

    PubMed

    Ma, Dehua; Chen, Lujun; Zhu, Xiaobiao; Li, Feifei; Liu, Cong; Liu, Rui

    2014-05-01

    To date, toxicological studies of endocrine disrupting chemicals (EDCs) have typically focused on single chemical exposures and associated effects. However, exposure to EDCs mixtures in the environment is common. Antiandrogens represent a group of EDCs, which draw increasing attention due to their resultant demasculinization and sexual disruption of aquatic organisms. Although there are a number of in vivo and in vitro studies investigating the combined effects of antiandrogen mixtures, these studies are mainly on selected model compounds such as flutamide, procymidone, and vinclozolin. The aim of the present study is to investigate the combined antiandrogenic effects of parabens, which are widely used antiandrogens in industrial and domestic commodities. A yeast-based human androgen receptor (hAR) assay (YAS) was applied to assess the antiandrogenic activities of n-propylparaben (nPrP), iso-propylparaben (iPrP), methylparaben (MeP), and 4-n-pentylphenol (PeP), as well as the binary mixtures of nPrP with each of the other three antiandrogens. All of the four compounds could exhibit antiandrogenic activity via the hAR. A linear interaction model was applied to quantitatively analyze the interaction between nPrP and each of the other three antiandrogens. The isoboles method was modified to show the variation of combined effects as the concentrations of mixed antiandrogens were changed. Graphs were constructed to show isoeffective curves of three binary mixtures based on the fitted linear interaction model and to evaluate the interaction of the mixed antiandrogens (synergism or antagonism). The combined effect of equimolar combinations of the three mixtures was also considered with the nonlinear isoboles method. The main effect parameters and interaction effect parameters in the linear interaction models of the three mixtures were different from zero. The results showed that any two antiandrogens in their binary mixtures tended to exert equal antiandrogenic activity

  9. Simple and complex disorder in binary mixtures with benzene as a common solvent.

    PubMed

    Požar, Martina; Seguier, Jean-Baptiste; Guerche, Jonas; Mazighi, Redha; Zoranić, Larisa; Mijaković, Marijana; Kežić-Lovrinčević, Bernarda; Sokolić, Franjo; Perera, Aurélien

    2015-04-21

    Substituting benzene for water in computer simulations of binary mixtures allows one to study the various forms of disorder, without the complications often encountered in aqueous mixtures. In particular, we study the relationship between the local order generated by different types of molecular interactions and the nature of the global disorder, by analyzing the relationship between the concentration fluctuations and the correlation functions and the associated structure factors. Alkane-benzene mixtures are very close to ideal mixtures, despite appreciable short range shape mismatch interactions, acetone-benzene mixtures appear as a good example of regular mixtures, and ethanol-benzene mixtures show large micro-segregation. In the latter case, we can unambiguously demonstrate, unlike in the case of water, the appearance of domain-domain correlations, both in the correlation functions and the structure factor calculated in computer simulations. This finding helps to confirm the existence of a pre-peak in the structure factor associated with the micro-heterogeneity, which was speculated from several of our previous simulations of aqueous-alcohol mixtures. The fact that benzene as a solvent allows us to solve some of the problems that could not be solved with water points towards some of the particularities of water as a solvent, which we discuss herein. The concept of molecular emulsion put forward in our earlier work is useful in formulating these differences between water and benzene through the analogy with direct and inverse micellar aggregates.

  10. Interaction between natural antioxidants derived from cinnamon and cocoa in binary and complex mixtures.

    PubMed

    Muhammad, Dimas Rahadian Aji; Praseptiangga, Danar; Van de Walle, Davy; Dewettinck, Koen

    2017-09-15

    Cinnamon and cocoa are known to be valuable sources of bioactive phytochemicals, mainly the polyphenols. This paper investigates the potential antioxidant activity of cinnamon and cocoa extract and the interaction of their mixtures by various in vitro tests. Moreover, the combination effect of their constituents in a binary mixture was studied. Two representative active compounds of chocolate (epicatechin, catechin) were combined with seven of cinnamon (gallic acid, tannic acid, quercetin, sinapic acid, cinnamic acid, eugenol and cinnamaldehyde) in multilevel ratios. The results indicate that the addition of the cinnamon extract significantly increased the antioxidant activity of the cocoa extract. The interaction ranged from synergetic to antagonistic. The interaction was less synergetic when cinnamon extract was added in higher proportion. The interaction of their constituents substantially influenced the antioxidant activity of the mixture and was dependent on the ratio. The kinetics' study could elucidate how the polyphenols work in a mixture. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Synergism and Combinatorial Coding for Binary Odor Mixture Perception in Drosophila

    PubMed Central

    Chakraborty, Tuhin Subhra; Siddiqi, Obaid

    2016-01-01

    Most odors in the natural environment are mixtures of several compounds. Olfactory receptors housed in the olfactory sensory neurons detect these odors and transmit the information to the brain, leading to decision-making. But whether the olfactory system detects the ingredients of a mixture separately or treats mixtures as different entities is not well understood. Using Drosophila melanogaster as a model system, we have demonstrated that fruit flies perceive binary odor mixtures in a manner that is heavily dependent on both the proportion and the degree of dilution of the components, suggesting a combinatorial coding at the peripheral level. This coding strategy appears to be receptor specific and is independent of interneuronal interactions. PMID:27588303

  12. Mutual diffusion in binary mixtures of ionic liquids and molecular liquids by dynamic light scattering (DLS).

    PubMed

    Rausch, Michael Heinrich; Lehmann, Julia; Leipertz, Alfred; Fröba, Andreas Paul

    2011-05-28

    The present study shows that dynamic light scattering (DLS) is capable of measuring mutual diffusion coefficients for binary mixtures of ionic liquids (ILs) with different molecular liquids over the complete composition range. Evidence is given that the light scattering signals are related to true molecular binary diffusion. The method stands out due to its ability to work non-invasively in macroscopic thermodynamic equilibrium with reasonable accuracy and within convenient measurement periods. Compared with other techniques, mixtures with distinctly higher viscosities can be probed. For exemplary binary mixtures of 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO(4)]) with acetone, acetonitrile, dichloromethane, ethanol, or water as well as of 1-ethyl-3-methylimidazolium methanesulfonate ([EMIM][MeSO(3)]) with acetone, water, or methanol, mutual diffusivity data were measured over a wide range of composition at a temperature of 293.15 K. In general, the mutual diffusivity increases with increasing mole fraction of the molecular liquid and similarities to aqueous solutions of classical inorganic salts can be found. The characteristic behavior of the mutual diffusion coefficients is influenced by the nature of the chosen molecular liquid. For IL water mixtures, low light scattering intensities were observed despite the large refractive index difference of the pure components. The reason for this behavior may be the existence of water clusters in the mixtures. Additional measurements for IL acetone mixtures at temperatures ranging from 278.15 K to 323.15 K showed that the temperature dependence of the mutual diffusivity can be represented by Arrhenius functions and is increasing for decreasing mole fractions of acetone.

  13. 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

  14. Regulation of dispersion of carbon nanotubes in binary water+1-Cyclohexyl-2-pyrrolidone mixtures

    NASA Astrophysics Data System (ADS)

    Deriabina, O.; Lebovka, N.; Bulavin, L.; Goncharuk, A.

    2014-05-01

    The microstructure and electrical conductivity of suspensions of multi-walled carbon nanotubes (MWCNTs) in binary water+1-Cyclohexyl-2-pyrrolidone (CHP) liquid mixtures were studied in the temperature interval of 253-318 K, in the heating and cooling cycles. The concentration of MWCNTs was varied in the interval between 0 and 1 wt% and the content of water in a binary mixture X=[water]/([CHP]+[water]) was varied within 0-1.0. The experimental data have shown that dispersing quality of MWCNTs in a mixture of good (CHP) and bad (water) solvents may be finely regulated by adjustment of composition of the CHP+water mixtures. The aggregation ability of MWCNTs in dependence on X was discussed. The surface of MWCNT clusters was highly tortuous, its fractal dimension df increased with increase of X, approaching ≈1.9 at X→1. It was concluded that the surface tension is not suitable characteristic for prediction of dispersion ability in the mixture of good and bad solvents. The electrical conductivity data evidenced the presence of a fuzzy-type percolation with multiple thresholds in the systems under investigation. This behavior was explained by formation of different percolation networks in dependence of MWCNT concentration.

  15. Grafting of vinyl acetate-ethylacrylate binary monomer mixture onto guar gum.

    PubMed

    Singh, Vandana; Singh, Angela; Joshi, Sneha; Malviya, Tulika

    2016-03-01

    Present article reports on guar gum (GG) functionalization through graftcopolymerization of vinylacetate (VAC) and ethylacrylate (EA) from their binary mixtures. The potassium persulfate/ascorbic acid (KPS/AA) redox initiator system has been used for the binary grafting under the previously optimized conditions for VAC grafting at guar gum. The concentration of ascorbic acid (AA), persulfate (KPS), and grafting temperature were varied to optimize the binary grafting. A preliminary investigation revealed that the copolymer has excellent ability to capture Hg(II) from aqueous solution. It was observed that the optimum % grafting sample (CP3) was best at Hg(II) adsorption. CP3 and mercury loaded CP3 (CP3-Hg) have been extensively characterized using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Thermo gravimetric analysis (TGA) and a plausible mechanism for the grafting has been proposed.

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

    PubMed

    Gobrogge, Eric A; Walker, Robert A

    2014-08-07

    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.

  17. Detection And Discrimination Of Pure Gases And Binary Mixtures Using A Single Microcantilever

    SciTech Connect

    Loui, A; Sirbuly, D J; Elhadj, S; McCall, S K; Hart, B R; Ratto, T V

    2009-08-06

    A new method for detecting and discriminating pure gases and binary mixtures has been investigated. This approach combines two distinct physical mechanisms within a single piezoresistive microcantilever: heat dissipation and resonant damping in the viscous regime. An experimental study of the heat dissipation mechanism indicates that the sensor response is directly correlated to the thermal conductivity of the gaseous analyte. A theoretical data set of resonant damping was generated corresponding to the gas mixtures examined in the thermal response experiments. The combination of the thermal and resonant response data yields more distinct analyte signatures that cannot otherwise be obtained from the detection modes individually.

  18. Thermophoretic force on micro- and nanoparticles in dilute binary gas mixtures.

    PubMed

    Wang, Jun; Li, Zhigang

    2011-08-01

    We theoretically investigate the thermophoretic force on spherical particles in binary monatomic gas mixtures in the free molecular regime. Based on gas kinetic theory and by considering the gas-particle interactions, we derive the analytical formulas of the thermophoretic force for two limiting gas-particle collision models; namely, specular and diffuse scattering scenarios. The formulas are consistent with those in simple gases and apply to both micro- and nanoparticles; for the latter the intermolecular interactions are important. As an example, the thermophoretic force on Ag nanoparticles in He-Ar mixtures is illustrated.

  19. Capillary condensation of a binary mixture in slit-like pores.

    PubMed

    Bucior, Katarzyna; Patrykiejew, Andrzej; Pizio, Orest; Sokołowski, Stefan

    2003-03-15

    We investigate the capillary condensation of two model fluid mixtures in slit-like pores, which exhibit different demixing properties in the bulk phase. The interactions between adsorbate particles are modeled by using Lennard-Jones (12,6) potentials and the adsorbing potentials are of the Lennard-Jones (9,3) type. The calculations are performed for different pore widths and at different concentrations of the bulk gas, by means of density functional theory. We evaluate the capillary phase diagrams and discuss their dependence on the parameters of the model. Our calculations indicate that a binary mixture confined to a slit-like pore may exhibit rich phase behavior.

  20. Thermodynamic aspects of phase equilibrium in binary water-organic solvent mixtures

    NASA Astrophysics Data System (ADS)

    Mizerovskii, L. N.

    2017-02-01

    It is shown that the boundary curves of liquid equilibria in binary systems characterize the temperature-concentration boundary of the existence of homogeneous mixtures whose formation is not accompanied by changes in the Gibbs energy of the system and are a combination of two branches that do not convert into each other but intersect at the temperature of homogenization of a mixture of critical composition. The phase diagrams of a number of water-organic solvent systems are analyzed to determine the thermodynamic particularities of the latter.

  1. Fractional and continuous wavelet transforms for the simultaneous spectral analysis of a binary mixture system

    NASA Astrophysics Data System (ADS)

    Dinç, Erdal; Büker, Eda; Baleanu, Dumitru

    2011-12-01

    A combined application of the fractional wavelet transform-continuous wavelet transform to the quantitative resolution of the overlapping signals of olmesartan modoxomil and hydrochlorothiazide in a binary mixture was presented. In this work the recorded absorption signals of two compounds in the range 4-12 μg/mL olmesartan and 2-10 μg/mL hydrochlorothiazide were processed by the fractional transform approach and with the continuous wavelet transform, respectively. The proposed combined complex signal analysis method was validated by analyzing the synthetic binary mixtures of the related compound. By analyzing the statistical parameters we conclude that the new approach is suitable to be used for the quality control of the commercial samples of compounds.

  2. The toxicity of binary mixture of Cu (II) ion and phenols on Tetrahymena thermophila.

    PubMed

    Luo, Hui; Li, Xi; Fang, Tingting; Liu, Peng; Zhang, Chaocan; Xie, Hao; Sun, Enjie

    2015-03-01

    The toxicity of binary mixture of Cu(2+) and phenols (phenol; o-nitrophenol; m-nitrophenol; p-nitrophenol) was evaluated using Tetrahymena thermophila as the model organism, by microcalorimetry, optical density, field emission scanning electron microscope (FESEM) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The growth curves and metabolic properties of Tetrahymena exposed to Cu(2+) and phenols were monitored by microcalorimetry. Binary mixture toxicity changed with the concentration of Cu(2+)/phenols and the order of toxicity was Cu(2+)/phenol

  3. Experimental observation of structural crossover in binary mixtures of colloidal hard spheres.

    PubMed

    Baumgartl, Jörg; Dullens, Roel P A; Dijkstra, Marjolein; Roth, Roland; Bechinger, Clemens

    2007-05-11

    Using confocal microscopy, we investigate the structure of binary mixtures of colloidal hard spheres with size ratio q=0.61. As a function of the packing fraction of the two particle species, we observe a marked change of the dominant wavelength in the pair-correlation function. This behavior is in excellent agreement with a recently predicted structural crossover in such mixtures. In addition, the repercussions of structural crossover on the real-space structure of a binary fluid are analyzed. We suggest a relation between crossover and the lateral extension of networks containing only equally-sized particles that are connected by nearest-neighbor bonds. This is supported by Monte Carlo simulations which are performed at different packing fractions and size ratios.

  4. Communication: Virial coefficients and demixing in highly asymmetric binary additive hard-sphere mixtures.

    PubMed

    López de Haro, Mariano; Tejero, Carlos F; Santos, Andrés

    2013-04-28

    The problem of demixing in a binary fluid mixture of highly asymmetric additive hard spheres is revisited. A comparison is presented between the results derived previously using truncated virial expansions for three finite size ratios with those that one obtains with the same approach in the extreme case in which one of the components consists of point particles. Since this latter system is known not to exhibit fluid-fluid segregation, the similarity observed for the behavior of the critical constants arising in the truncated series in all instances, while not being conclusive, may cast serious doubts as to the actual existence of a demixing fluid-fluid transition in disparate-sized binary additive hard-sphere mixtures.

  5. Simultaneous spectrophotometric determination of binary mixtures of surfactants using continuous wavelet transformation.

    PubMed

    Afkhami, Abbas; Nematollahi, Davood; Madrakian, Tayyebeh; Abbasi-Tarighat, Maryam; Hajihadi, Mitra

    2009-07-30

    This work presents a simple, rapid, and novel method for simultaneous determination of binary mixtures of some surfactants using continuous wavelet transformation. The method is based on the difference in the effect of surfactants Cetyltrimethylammoniumbromide (CTAB), dodecyl trimethylammonium bromide (DTAB), cetylpyridinium bromide (CPB) and TritonX-100 (TX-100) on the absorption spectra of complex of Beryllium with Chrome Azurol S (CAS) at pH 5.4. Binary mixtures of CTAB-DTAB, DTAB-CPB and CTAB-TX-100 were analyzed without prior separation steps. Different mother wavelets from the family of continuous wavelet transforms were selected and applied under the optimal conditions for simultaneous determinations. The proposed methods, under the working conditions, were successfully applied to simultaneous determination of surfactants in hair conditioner and mouthwash samples.

  6. Preferential solvation of lysozyme in dimethyl sulfoxide/water binary mixture probed by terahertz spectroscopy.

    PubMed

    Das, Dipak Kumar; Patra, Animesh; Mitra, Rajib Kumar

    2016-09-01

    We report the changes in the hydration dynamics around a model protein hen egg white lysozyme (HEWL) in water-dimethyl sulfoxide (DMSO) binary mixture using THz time domain spectroscopy (TTDS) technique. DMSO molecules get preferentially solvated at the protein surface, as indicated by circular dichroism (CD) and Fourier transform infrared (FTIR) study in the mid-infrared region, resulting in a conformational change in the protein, which consequently modifies the associated hydration dynamics. As a control we also study the collective hydration dynamics of water-DMSO binary mixture and it is found that it follows a non-ideal behavior owing to the formation of DMSO-water clusters. It is observed that the cooperative dynamics of water at the protein surface does follow the DMSO-mediated conformational modulation of the protein. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Thermo-acoustical molecular interaction study in binary mixtures of glycerol and ethylene glycol

    NASA Astrophysics Data System (ADS)

    Kaur, Kirandeep; Juglan, K. C.; Kumar, Harsh

    2017-07-01

    Ultrasonic velocity, density and viscosity are measured over the entire composition range for binary liquid mixtures of glycerol (CH2OH-CHOH-CH2OH) and ethylene glycol (HOCH2CH2OH) at different temperatures and constant frequency of 2MHz using ultrasonic interferometer, specific gravity bottle and viscometer respectively. Measured experimental values are used to obtained various acoustical parameters such as adiabatic compressibility, acoustic impedance, intermolecular free length, relaxation time, ultrasonic attenuation, effective molar weight, free volume, available volume, molar volume, Wada's constant, Rao's constant, Vander Waal's constant, internal pressure, Gibb's free energy and enthalpy. The variation in acoustical parameters are interpreted in terms of molecular interactions between the components of molecules of binary liquid mixtures.

  8. Exact results for the jammed state of binary mixtures of superdisks on the plane

    NASA Astrophysics Data System (ADS)

    Švrakić, N. M.; Aleksić, Branislav N.; Belić, Milivoj R.

    2016-01-01

    By analytical and numerical methods we investigate the late stage deposition of binary mixtures of oriented "superdisks" on a plane. Superdisks are objects bounded by Lamé curves | x | 2 p +| y | 2 p = 1, where deformation parameter p controls their size and shape. For deposition of single-type superdisks, the maximum packing and jamming densities are known to be nonanalytic at p = 0.5. For binary mixtures of superdisks, we discover that nonanalyticities form a locus of points separating "phase diagram" of shape combinations into regions with different excluded-area constructions. An analytical expression for this phase boundary and exact constructions of the excluded-areas are presented. The corresponding saturation coverages are obtained by extensive numerical Monte Carlo simulations.

  9. Reaction of singlet oxygen with thioanisole in ionic liquid-acetonitrile binary mixtures.

    PubMed

    Baciocchi, Enrico; Chiappe, Cinzia; Fasciani, Chiara; Lanzalunga, Osvaldo; Lapi, Andrea

    2010-11-19

    A study of the reaction of thioanisole with singlet oxygen in different ionic liquid-acetonitrile binary mixtures has shown that ILs are able to accelerate the thioanisole sulfoxidation when used as additives. With imidazolium ILs, the maximum efficiency is reached at x(IL) ∼ 0.1-0.2, whereas for the pyrrolidinium IL a plateau is reached. These results are discussed in terms of the ILs' tendency to form ionic aggregates and of differences in sulfoxidation reaction mechanism.

  10. Kinetic model of phase separation in binary mixtures with hard mobile impurities.

    PubMed

    Ginzburg, V V; Peng, G; Qiu, F; Jasnow, D; Balazs, A C

    1999-10-01

    We develop a mean-field rate-equation model for the kinetics of phase separation in binary mixtures with hard mobile impurities. For impurities preferentially wet by one of the components, the phase separation is arrested in the late stage. The "steady-state" domain size depends strongly on both the particle diffusion constant and the particle concentration. We compare theoretical results with the simulation data and find good qualitative agreement.

  11. Viscosities of Binary Mixtures Containing Isomeric Chlorobutanes and Diisopropylether: Experimental and Predicted Values

    NASA Astrophysics Data System (ADS)

    Montaño, D.; Guerrero, H.; Bandrés, I.; López, M. C.; Lafuente, Carlos

    2010-03-01

    In this work, viscosities of binary mixtures of isomeric chlorobutanes with diisopropylether have been determined as a function of composition under atmospheric pressure and in the temperature range from 283.15 K to 313.15 K with steps of 5 K. Kinematics viscosities were measured using an Ubbelohde viscosimeter; absolute viscosities were obtained from kinematic viscosities and densities. Finally, we have used the Asfour method for predicting the dependence of viscosity with composition and comparing it with our experimental data.

  12. Control of Native Spoilage Yeast on Dealcoholized Red Wine by Preservatives Alone and in Binary Mixtures.

    PubMed

    Sánchez-Rubio, Marta; Guerrouj, Kamal; Taboada-Rodríguez, Amaury; López-Gómez, Antonio; Marín-Iniesta, Fulgencio

    2017-09-01

    In order to preserve a commercial dealcoholized red wine (DRW), a study with 4 preservatives and binary mixtures of them were performed against 2 native spoilage yeasts: Rhodotorula mucilaginosa and Saccharomyces cerevisiae. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) for potassium sorbate, sodium benzoate, sodium metabisulfite and dimethyl dicarbonate (DMDC) were evaluated in DRW stored at 25 °C. MICs of potassium sorbate and sodium metabisulfite were 250 and 60 mg/kg, respectively for both target strains. However for sodium benzoate, differences between yeasts were found; R. mucilaginosa was inhibited at 125 mg/kg, while S. cerevisiae at 250 mg/kg. Regarding MFC, differences between strains were only found for sodium metabisulfite obtaining a MFC of 500 mg/kg for R. mucilaginosa and a MFC of 250 mg/kg for S. cerevisiae. Potassium sorbate and sodium benzoate showed the MFC at 1000 mg/kg and DMDC at 200 mg/kg. Regarding the effect of binary mixtures the Fractional Fungicidal Concentration Index (FFCi ) methodology showed that binary mixtures of 100 mg/kg DMDC/200 mg/kg potassium sorbate (FFCi = 0.7) and 50 mg/kg DMDC / 400 mg/kg sodium benzoate (FFCi = 0.65) have both synergistic effect against the 2 target strains. These binary mixtures can control the growth of spoilage yeasts in DRW without metabisulfite addition. The results of this work may be important in preserving the health of DRW consumers by eliminating the use of metabisulfite and reducing the risk of growth of R. mucilagosa, recently recognized as an emerging pathogen. © 2017 Institute of Food Technologists®.

  13. Implementation of an ultrasonic instrument for simultaneous mixture and flow analysis of binary gas systems

    SciTech Connect

    Alhroob, M.; Boyd, G.; Hasib, A.; Pearson, B.; Srauss, M.; Young, J.; Bates, R.; Bitadze, A.; Battistin, M.; Berry, S.; Bonneau, P.; Botelho-Direito, J.; Bozza, G.; Crespo-Lopez, O.; DiGirolamo, B.; Favre, G.; Godlewski, J.; Lombard, D.; Zwalinski, L.; Bousson, N.; Hallewell, G.; Mathieu, M.; Rozanov, A.; Deterre, C.; O'Rourke, A.; Doubek, M.; Vacek, V.; Degeorge, C.; Katunin, S.; Langevin, N.; McMahon, S.; Nagai, K.; Robinson, D.; Rossi, C.

    2015-07-01

    Precision ultrasonic measurements in binary gas systems provide continuous real-time monitoring of mixture composition and flow. Using custom micro-controller-based electronics, we have developed an ultrasonic instrument, with numerous potential applications, capable of making continuous high-precision sound velocity measurements. The instrument measures sound transit times along two opposite directions aligned parallel to - or obliquely crossing - the gas flow. The difference between the two measured times yields the gas flow rate while their average gives the sound velocity, which can be compared with a sound velocity vs. molar composition look-up table for the binary mixture at a given temperature and pressure. The look-up table may be generated from prior measurements in known mixtures of the two components, from theoretical calculations, or from a combination of the two. We describe the instrument and its performance within numerous applications in the ATLAS experiment at the CERN Large Hadron Collider (LHC). The instrument can be of interest in other areas where continuous in-situ binary gas analysis and flowmetry are required. (authors)

  14. Transport Properties of He-N{sub 2} Binary Gas Mixtures for CBC Space Applications

    SciTech Connect

    Tournier, Jean-Michel P.; El-Genk, Mohamed S.

    2008-01-21

    In order to reduce the size and mass of the single-shaft turbo-machines, with little impact on the size of the heat transfer components in the CBC loop, He-Xe binary mixture with a molecular weight of 40 g/mole has been the working fluid of choice in space nuclear reactor power systems with Close Brayton Cycle (CBC) for energy conversion. This working fluid is also a suitable coolant for the fission reactors heat source designed with fast neutron energy spectra. For space nuclear reactors with thermal neutron energy spectra, however, the high capture neutron cross-section of Xe will reduce the beginning-of-life excess reactivity of the reactor, decreasing its effective operation lifetime. In addition, the neutron activation of Xe in the reactor will introduce a radioactivity source term in the CBC loop. Alternative working fluids with no activation concerns and comparable performance are N{sub 2} and the binary mixtures of He-N{sub 2}. This paper calculates the transport properties of these working fluids and compares their values to those of noble gas binary mixtures at the temperatures and pressures expected in CBC space reactor power system applications. Also investigated is the impact of using these working fluids on the pressure losses, heat transfer coefficient, and the aerodynamic loading of the blades in the CBC turbo-machines.

  15. The Shape of Solar Cycles Described by a Simplified Binary Mixture of Gaussian Functions

    NASA Astrophysics Data System (ADS)

    Li, F. Y.; Xiang, N. B.; Kong, D. F.; Xie, J. L.

    2017-01-01

    Sunspot cycles usually present a double-peak structure. This work is devoted to using a function to describe the shape of sunspot cycles, including bimodal cycles, and we find that the shape of sunspot cycles can be described by a binary mixture of Gaussian functions with six parameters, two amplitudes, two gradients of curve, and two rising times, and the parameters could be reduced to three. The fitting result of this binary mixture of Gaussian functions is compared with some other functions used previously in the literature, and this function works pretty well, especially at cycle peaks. It is worth mentioning that the function can describe well the shape of those sunspot cycles that show double peaks, and it is superior to the binary mixture of the Laplace functions that was once utilized. The Solar Influences Data Analysis Center, on behalf of the World Data Center, recently issued a new version (version 2) of sunspot number. The characteristics of sunspot cycles are investigated, based on the function description of the new version.

  16. Transport Properties of He-N2 Binary Gas Mixtures for CBC Space Applications

    NASA Astrophysics Data System (ADS)

    Tournier, Jean-Michel P.; El-Genk, Mohamed S.

    2008-01-01

    In order to reduce the size and mass of the single-shaft turbo-machines, with little impact on the size of the heat transfer components in the CBC loop, He-Xe binary mixture with a molecular weight of 40 g/mole has been the working fluid of choice in space nuclear reactor power systems with Close Brayton Cycle (CBC) for energy conversion. This working fluid is also a suitable coolant for the fission reactors heat source designed with fast neutron energy spectra. For space nuclear reactors with thermal neutron energy spectra, however, the high capture neutron cross-section of Xe will reduce the beginning-of-life excess reactivity of the reactor, decreasing its effective operation lifetime. In addition, the neutron activation of Xe in the reactor will introduce a radioactivity source term in the CBC loop. Alternative working fluids with no activation concerns and comparable performance are N2 and the binary mixtures of He-N2. This paper calculates the transport properties of these working fluids and compares their values to those of noble gas binary mixtures at the temperatures and pressures expected in CBC space reactor power system applications. Also investigated is the impact of using these working fluids on the pressure losses, heat transfer coefficient, and the aerodynamic loading of the blades in the CBC turbo-machines.

  17. Theoretical and experimental examination of SFG polarization analysis at acetonitrile-water solution surfaces.

    PubMed

    Saito, Kengo; Peng, Qiling; Qiao, Lin; Wang, Lin; Joutsuka, Tatsuya; Ishiyama, Tatsuya; Ye, Shen; Morita, Akihiro

    2017-03-16

    Sum frequency generation (SFG) spectroscopy is widely used to observe molecular orientation at interfaces through a combination of various types of polarization. The present work thoroughly examines the relation between the polarization dependence of SFG signals and the molecular orientation, by comparing SFG measurements and molecular dynamics (MD) simulations of acetonitrile/water solutions. The present SFG experiment and MD simulations yield quite consistent results on the ratios of χ((2)) elements, supporting the reliability of both means. However, the subsequent polarization analysis tends to derive more upright tilt angles of acetonitrile than the direct MD calculations. The reasons for discrepancy are examined in terms of three issues; (i) anisotropy of the Raman tensor, (ii) cross-correlation, and (iii) orientational distribution. The analysis revealed that the issues (i) and (iii) are the main causes of errors in the conventional polarization analysis of SFG spectra. In methyl CH stretching, the anisotropy of Raman tensor cannot be estimated from the simple bond polarizability model. The neglect of the orientational distribution is shown to systematically underestimate the tilt angle of acetonitrile. Further refined use of polarization analysis in collaboration with MD simulations should be proposed.

  18. Joint toxic action of binary metal mixtures of copper, manganese and nickel to Paronychiurus kimi (Collembola).

    PubMed

    Son, Jino; Lee, Yun-Sik; Kim, Yongeun; Shin, Key-Il; Hyun, Seunghun; Cho, Kijong

    2016-10-01

    The joint toxic effects of binary metal mixtures of copper (Cu), manganese (Mn) and nickel (Ni) on reproduction of Paronhchiurus kimi (Lee) was evaluated using a toxic unit (TU) approach by judging additivity across a range of effect levels (10-90%). For all metal mixtures, the joint toxic effects of metal mixtures on reproduction of P. kimi decreased in a TU-dependent manner. The joint toxic effects of metal mixtures also changed from less than additive to more than additive at an effect level lower than or equal to 50%, while a more than additive toxic effects were apparent at higher effect levels. These results indicate that the joint toxicity of metal mixtures is substantially different from that of individual metals based on additivity. Moreover, the close relationship of toxicity to effect level suggests that it is necessary to encompass a whole range of effect levels rather than a specific effect level when judging mixture toxicity. In conclusion, the less than additive toxicity at low effect levels suggests that the additivity assumption is sufficiently conservative to warrant predicting joint toxicity of metal mixtures, which may give an additional margin of safety when setting soil quality standards for ecological risk assessment.

  19. Three Boundary Conditions for Computing the Fixed-Point Property in Binary Mixture Data.

    PubMed

    van Maanen, Leendert; Couto, Joaquina; Lebreton, Mael

    2016-01-01

    The notion of "mixtures" has become pervasive in behavioral and cognitive sciences, due to the success of dual-process theories of cognition. However, providing support for such dual-process theories is not trivial, as it crucially requires properties in the data that are specific to mixture of cognitive processes. In theory, one such property could be the fixed-point property of binary mixture data, applied-for instance- to response times. In that case, the fixed-point property entails that response time distributions obtained in an experiment in which the mixture proportion is manipulated would have a common density point. In the current article, we discuss the application of the fixed-point property and identify three boundary conditions under which the fixed-point property will not be interpretable. In Boundary condition 1, a finding in support of the fixed-point will be mute because of a lack of difference between conditions. Boundary condition 2 refers to the case in which the extreme conditions are so different that a mixture may display bimodality. In this case, a mixture hypothesis is clearly supported, yet the fixed-point may not be found. In Boundary condition 3 the fixed-point may also not be present, yet a mixture might still exist but is occluded due to additional changes in behavior. Finding the fixed-property provides strong support for a dual-process account, yet the boundary conditions that we identify should be considered before making inferences about underlying psychological processes.

  20. Studying of crystal growth and overall crystallization of naproxen from binary mixtures.

    PubMed

    Kaminska, E; Madejczyk, O; Tarnacka, M; Jurkiewicz, K; Kaminski, K; Paluch, M

    2017-04-01

    Broadband dielectric spectroscopy (BDS) and differential scanning calorimetry (DSC) were applied to investigate the molecular dynamics and phase transitions in binary mixtures composed of naproxen (NAP) and acetylated saccharides: maltose (acMAL) and sucrose (acSUC). Moreover, the application of BDS method and optical microscopy enabled us to study both crystallization kinetics and crystal growth of naproxen from the solid dispersions with the highest content of modified carbohydrates (1:5wt ratio). It was found that the activation barriers of crystallization estimated from dielectric measurements are completely different for both studied herein mixtures. Much higher Ea (=205kJ/mol) was obtained for NAP-acMAL solid dispersion. It is probably due to simultaneous crystallization of both components of the mixture. On the other hand, lower value of Ea in the case of NAP-acSUC solid dispersion (81kJ/mol) indicated, that naproxen is the only crystallizing compound. This hypothesis was confirmed by X-ray diffraction studies. We also suggested that specific intermolecular dipole-dipole interactions between active substance and excipient may be an alternative explanation for the difference between activation barrier obtained for NAP-acMAL and NAP-acSUC binary mixtures. Furthermore, optical measurements showed that the activation energy for crystal growth of naproxen increases in binary mixtures. They also revealed that both excipients: acMAL and acSUC move the temperature of the maximum of crystal growth towards lower temperatures. Interestingly, this maximum occurs for nearly the same structural relaxation time, which is a good approximation of viscosity, for all samples. Finally, it was also noticed that although naproxen crystallizes to the same polymorphic form in both systems, there are some differences in morphology of obtained crystals. Thus, the observed behavior may have a significant impact on the bioavailability and dissolution rate of API produced in that way

  1. The effects of binary UV filter mixtures on the midge Chironomus riparius.

    PubMed

    Ozáez, Irene; Morcillo, Gloria; Martínez-Guitarte, José-Luis

    2016-06-15

    Organic ultraviolet (UV) filters are used in a wide variety of products, including cosmetics, to prevent damage from UV light in tissues and industrial materials. Their extensive use has raised concerns about potential adverse effects in human health and aquatic ecosystems that accumulate these pollutants. To increase sun radiation protection, UV filters are commonly used in mixtures. Here, we studied the toxicity of binary mixtures of 4-methylbenzylidene camphor (4MBC), octyl-methoxycinnamate (OMC), and benzophenone-3 (BP-3), by evaluating the larval mortality of Chironomus riparius. Also molecular endpoints have been analyzed, including alterations in the expression levels of a gene related with the endocrine system (EcR, ecdysone receptor) and a gene related with the stress response (hsp70, heat shock protein 70). The results showed that the mortality caused by binary mixtures was similar to that observed for each compound alone; however, some differences in LC50 were observed between groups. Gene expression analysis showed that EcR mRNA levels increased in the presence of 0.1mg/L 4MBC but returned to normal levels after exposure to mixtures of 4MBC with 0.1, 1, and 10mg/L of BP-3 or OMC. In contrast, the hsp70 mRNA levels increased after exposure to the combinations tested of 4MBC and BP-3 or OMC mixtures. These data suggest that 4MBC, BP-3, and OMC may have antagonist effects on EcR gene transcription and a synergistic effect on hsp70 gene activation. This is the first experimental study to show the complex patterned effects of UV filter mixtures on invertebrates. The data suggest that the interactions within these chemicals mixtures are complex and show diverse effects on various endpoints.

  2. Picosecond reorientational dynamics of polar dye probes in binary aqueous mixtures

    NASA Astrophysics Data System (ADS)

    Dutt, G. B.; Doraiswamy, S.

    1992-02-01

    Picosecond time dependent fluorescence method has been used to measure the rotational reorientation times (τr) of three kinds of dye probes—oxazine 720 (a monocation), nile red (neutral but polar), and resorufin (a monoanion)—in a series of binary mixtures of water-amides, water-dipolar aprotics, and water-alcohols at 298 K. Most of the binary mixtures are characterized by the fact that at a particular composition (between 25% to 40% of the organic solvent in water), the viscosity (η) of the solution reaches a maximum value that is higher than the viscosities of the two solvents. As a consequence, the viscosity profile of the solution as a function of the organic solvent exhibits a bivaluedness, the extent of which is more, if the liquids are nearly isoviscous. The dielectric properties of the solution also change across the composition range. All the dyes show a near linear behavior of τr vs η in formamide-water, N-methylformamide-water, and methanol-water mixtures. A dual-valued profile for τr vs η is obtained for the cation oxazine 720 in the three dipolar aprotic mixtures (N, N-dimethylformamide-water, N, N-dimethylacetamide-water, and dimethylsulphoxide-water), with the rotational reorientation times being higher in the organic solvent-rich zone, compared to the corresponding isoviscous point in the water-rich zone. However, the anion resorufin shows a bivalued profile of τr vs η only in dimethylsulphoxide-water mixtures, while the neutral nile red shows a linear behavior in all the dipolar-aprotic water mixtures. A hook-type profile of τr vs η is seen for the anion resorufin in ethanol-, 1-propanol-, and 2-propanol-water mixtures and for the cation oxazine 720 in 1-propanol- and 2-propanol-water mixtures; but nile red shows no departure from linear behavior even in alcohol-water mixtures. The rotational dynamics of the cation oxazine 720 in dipolar aprotic-water mixtures is explained in terms of solvation since the dielectric friction is minimal

  3. Simultaneous determination of binary mixtures of sulfonylurea herbicides in water by first-derivative photochemically induced spectrofluorimetry.

    PubMed

    Coly, A; Aaron, J J

    2001-01-01

    First-derivative photochemically induced spectrofluorimetry (PIF-1D) is applied to the simultaneous determination of binary mixtures of 4 sulfonylurea herbicides in aqueous micellar samples. Synthetic binary mixtures of sulfometuronmethyl with chlorsulfuron, metsulfuron-methyl, and 3-rimsulfuron, respectively, are well resolved by using the zero-crossing point procedure. PIF-1D allows the determination of binary mixtures of these herbicides with linear dynamic ranges over about 2 orders of magnitude, limits of detection between 0.5 and 52 ng/mL, and relative standard deviations within 0.3-2.9%. Application to the determination of binary mixtures of these herbicides in spiked tap water samples yielded satisfactory recoveries (90-117%).

  4. Additive toxicity of binary mixtures of phototoxic polycyclic aromatic hydrocarbons to the oligochaete Lumbriculus variegatus.

    PubMed

    Erickson, R J; Ankley, G T; DeFoe, D L; Kosian, P A; Makynen, E A

    1999-01-01

    Toxicity of some polycyclic aromatic hydrocarbons (PAHs) can increase by an order of magnitude, or more, in the presence of solar ultraviolet (UV) radiation. In the environment, PAHs exist as complex mixtures, which generally would include multiple PAHs that could cause photoinduced toxicity. Hence, to accurately predict the potential ecological risk of phototoxic PAHs, it is critical to understand their joint toxicity. In this study, we exposed the oligochaete Lumbriculus variegatus to the phototoxic PAHs anthracene, fluoranthene, and pyrene, both singly and as binary mixtures for 96 h. Following this, the animals were exposed to UV light for an additional 96 h, during which periodic observations of mortality were made. Time-dependent phototoxicity of the binary PAH mixtures, expressed as a function of the product of UV light intensity and PAH dose (in the tissue of the animals), was adequately described using a concentration addition model. Given the probability that the PAHs examined acted via a common mechanism of action, this result was consistent with expectations. These data highlight the need to consider the combined photoactivation potential of PAH mixtures and provide the technical basis for a modeling approach to predict their ecological risk.

  5. Predicting the Solution Morphology of a Sulfonated Block Copolymer in Binary Solvent Mixtures

    NASA Astrophysics Data System (ADS)

    Griffin, Philip; Salmon, Grace; Ford, Jamie; Winey, Karen

    2015-03-01

    The physicochemical properties of solvent-casted block copolymer films are highly dependent on the microscopic morphology of the solutions from which they are cast. In order to achieve macroscopically homogenous polymer solutions, binary or higher-degree solvent mixtures are often required, which introduces additional complexity in understanding the molecular level interactions that control block copolymer self-assembly in solution. Using small angle x-ray scattering, we have explored the solution morphology in ternary blends of a sulfonated pentablock copolymer in select binary solvent mixtures over a range of solvent compositions and polymer concentrations. We have found that the solution morphologies in these ternary blends depend strongly on the composition of the solvent mixture. Furthermore, we demonstrate that the solvent-composition-dependent morphologies can be accurately predicted by quantifying the polymer/solvent interactions using Hansen solubility parameters. These studies are an important step toward developing a complete and predictive understanding of the solution morphology of complex polymer/solvent mixtures.

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

    PubMed

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

    2014-11-04

    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.

  7. Absorption spectra of e-beam-excited Ne, Ar, and Kr, pure and in binary mixtures.

    PubMed

    Levchenko, A O; Ustinovskii, N N; Zvorykin, V D

    2010-10-21

    A technique using the broadband emission of a laser plume as probe radiation is applied to record UV-visible (190-510 nm) absorption spectra of Ne, Ar, and Kr, pure and in binary mixtures under moderate e-beam excitation up to 1 MW/cm(3). In all the rare gases and mixtures, the absorption spectra show continuum related to Rg(2) (+) homonuclear ions [peaking at λ∼285, 295, and 320 nm in Ne, Ar, and Kr(Ar/Kr), respectively] and a number of atomic lines related mainly to Rg(∗)(ms) levels, where m is the lowest principal quantum number of the valence electron. In argon, a continuum related to Ar(2) (∗) (λ∼325 nm) is also recorded. There are also trains of narrow bands corresponding to Rg(2) (∗)(npπ (3)Π(g))←Rg(2) (∗)(msσ (3)Σ(u) (+)) transitions. All the spectral features mentioned above were reported in literature but have never been observed simultaneously. Although charge transfer to a homonuclear ion of the heavier additive is commonly believed to dominate in binary rare-gas mixtures, it is found in this study that in Ne/Kr mixture, the charge is finally transferred from the buffer gas Ne(2) (+) ion not to Kr(2) (+) but to heteronuclear NeKr(+) ion.

  8. Cadmium-induced olfactory dysfunction in rainbow trout: Effects of binary and quaternary metal mixtures.

    PubMed

    Dew, William A; Veldhoen, Nik; Carew, Amanda C; Helbing, Caren C; Pyle, Greg G

    2016-03-01

    A functioning olfactory response is essential for fish to be able to undertake essential behaviors. The majority of work investigating the effects of metals on the olfactory response of fish has focused on single-metal exposures. In this study we exposed rainbow trout to cadmium, copper, nickel, zinc, or a mixture of these four metals at or below the current Canadian Council of Ministers of the Environment guidelines for the protection of aquatic life. Measurement of olfactory acuity using an electro-olfactogram demonstrated that cadmium causes significant impairment of the entire olfactory system, while the other three metals or the mixture of all four metals did not. Binary mixtures with cadmium and each of the other metals demonstrated that nickel and zinc, but not copper, protect against cadmium-induced olfactory dysfunction. Testing was done to determine if the protection from cadmium-induced olfactory dysfunction could be explained by binding competition between cadmium and the other metals at the cell surface, or if the protection could be explained by an up-regulation of an intracellular detoxification pathway, namely metallothionein. This study is the first to measure the effects of binary and quaternary metal mixtures on the olfactory response of fish, something that will aid in future assessments of the effects of metals on the environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Gibbs ensemble Monte Carlo simulations of binary mixtures of methane, difluoromethane, and carbon dioxide.

    PubMed

    Do, Hainam; Wheatley, Richard J; Hirst, Jonathan D

    2010-03-25

    Gibbs ensemble Monte Carlo simulations were used to study the vapor-liquid equilibrium of binary mixtures of carbon dioxide + methane and carbon dioxide + difluoromethane. The potential forcefields we employ are all atomistic models, and have not previously been mixed together to study the vapor-liquid equilibrium of the binary mixtures. In addition, we characterize the microscopic structure of these liquid mixtures. In carbon dioxide + methane at 230 K and 56 bar, the microscopic structure of carbon dioxide in the mixture is the same as that in the pure liquid. In carbon dioxide + difluoromethane at 283 K and 56 bar, the presence of carbon dioxide does not noticeably perturb the liquid structure of difluoromethane, but the structure of carbon dioxide is subtly changed, due to a strong interaction between it and difluoromethane. The simulations in the isobaric-isothermal (NPT) ensemble agree well with the experimental data, except at the two extreme regions of the pressure range. The good agreement of most simulated state points with experimental data encourages one to develop more accurate potentials for predicting the thermodynamic properties of these systems as well as other complicated systems, which are less amenable to measurement by experiment.

  10. Insights into synergistic interactions in binary mixtures of chemical permeation enhancers for transdermal drug delivery.

    PubMed

    Karande, Pankaj; Jain, Amit; Mitragotri, Samir

    2006-09-28

    Chemical permeation enhancers (CPEs) are known to increase skin permeability to therapeutic drugs. Single chemicals, however, offer limited enhancements of skin permeability. Mixtures of chemicals can overcome this limitation owing to their synergistic interactions. However, identification of potent mixtures of chemicals requires screening of a large number of formulations. Discovery of CPE mixtures can be significantly accelerated by identifying patterns that occur in the existing data on CPEs. In this study, we systematically mine through a huge database on skin permeabilizing effect of over 4000 binary formulations generated by high throughput screening and extract general principles that govern the effect of binary combinations of chemicals on skin's barrier properties. Potencies and synergies of these formulations are analyzed to identify the role played by the formulation composition and chemistry. The analysis reveals several intuitive but some largely non-intuitive trends. For example, formulations made from enhancer mixtures are most potent when participating moieties are present in nearly equal fractions. Methyl pyrrolidone, a small molecule, is particularly effective in forming potent and synergistic enhancer formulations, and zwitterionic surfactants are more likely to feature in potent enhancers. Simple but invaluable rules like these will provide guiding principles for designing libraries to further speed up the formulation discovery process.

  11. Adsorption and separation of binary mixtures of noble gases on single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Foroutan, Masumeh; Taghavi Nasrabadi, Amir

    2011-02-01

    Adsorption and separation of binary mixtures of noble gases including Argon (Ar), Krypton (Kr), and Xenon (Xe) on (10,10) single-walled carbon nanotube (SWCNT) bundles is simulated by extensive equilibrium molecular dynamics (MD). Adsorption energies, diffusion coefficients, activation energies, and radial distribution functions (RDFs) were calculated to address the thermodynamics, transport and structural properties of adsorption process. The simulation results of exposing Ar-Kr, Ar-Xe, and Kr-Xe mixtures on (10,10) SWCNT bundles at temperatures of 75, 150, and 300 K, show that amount of adsorption is strongly influenced by the applied temperature. On the other hand, RDF plots show obviously that separation of binary gaseous mixture is occurred, where the heavier noble gas is adsorbed more than the lighter one in a selective manner by bundle. It is seen that the increase in the applied temperature results in more separation. These findings provide us a possible application of carbon nanotubes (CNTs) as efficient nanomaterials for separation and storage of gas mixtures.

  12. Surface tension of nitric oxide and its binary mixtures with krypton, methane, and ethene

    SciTech Connect

    Calado, J.C.G.; Santos Mendonca, A.F.S. dos; Saramago, B.J.V.; Soares, V.A.M.

    1997-05-15

    The surface tension of three binary liquid mixtures of NO with Kr, CH{sub 4}, and C{sub 2}H{sub 4} has been determined as a function of composition in the temperature range 102.0 to 119.0 K. These measurements are a contribution to the study of binary liquid mixtures in which one component is unassociated while the molecules of the other can associate between themselves. Nitric oxide is the simplest molecule capable of forming dimers, but not larger aggregates. This results in the surface tension of liquid nitric oxide having a strong temperature dependence: when the temperature increases the degree of dimerization decreases, contributing to a larger decrease of the surface tension. The surface tension of NO mixtures shows strong deviations from ideality. The mixtures containing Kr and CH{sub 4} exhibit negative deviations, while for the NO + C{sub 2}H{sub 4} system the surface tension shows a complex dependence on the composition. This strong departure from ideality had already been found for the bulk properties of these three systems. The surface tension of the CH{sub 4} + Kr system, already well characterized in the literature, was also measured to test the equipment.

  13. Flash-point prediction for binary partially miscible mixtures of flammable solvents.

    PubMed

    Liaw, Horng-Jang; Lu, Wen-Hung; Gerbaud, Vincent; Chen, Chan-Cheng

    2008-05-30

    Flash point is the most important variable used to characterize fire and explosion hazard of liquids. Herein, partially miscible mixtures are presented within the context of liquid-liquid extraction processes. This paper describes development of a model for predicting the flash point of binary partially miscible mixtures of flammable solvents. To confirm the predictive efficacy of the derived flash points, the model was verified by comparing the predicted values with the experimental data for the studied mixtures: methanol+octane; methanol+decane; acetone+decane; methanol+2,2,4-trimethylpentane; and, ethanol+tetradecane. Our results reveal that immiscibility in the two liquid phases should not be ignored in the prediction of flash point. Overall, the predictive results of this proposed model describe the experimental data well. Based on this evidence, therefore, it appears reasonable to suggest potential application for our model in assessment of fire and explosion hazards, and development of inherently safer designs for chemical processes containing binary partially miscible mixtures of flammable solvents.

  14. Experimental Droplet Study of Inverted Marangoni Effect of a Binary Liquid Mixture on a Nonuniform Heated Substrate.

    PubMed

    Ouenzerfi, Safouene; Harmand, Souad

    2016-03-15

    We present an experimental study on the inversion of the Marangoni effect of a binary mixture droplet under a horizontal temperature gradient. In particular, we studied the dynamics and the evaporation behavior under these conditions. We show that a binary mixture (97% water-3% butanol) droplet has a tendency to migrate to warmer areas, as opposed to spreading in pure fluids. During the evaporation process, we distinguish three stages of evaporation that are correlated to the dynamics of the droplet.

  15. Characterizing olfactory binary mixture interactions in Fischer 344 rats using behavioral reaction times.

    PubMed

    Yoder, Wendy M; Gaynor, Leslie; Windham, Ethan; Lyman, Michelle; Munizza, Olivia; Setlow, Barry; Bizon, Jennifer L; Smith, David W

    2015-06-01

    Response times provide essential subthreshold perceptual data that extend beyond accuracy alone. Behavioral reaction times (RTs) were used to characterize rats' ability to detect individual odorants in a series of complimentary binary odorant mixture ratios. We employed an automated, liquid-dilution olfactometer to train Fischer 344 rats (N = 8) on an odor identification task using nonreinforced probe trials. Binary mixture ratios composed of aliphatic odorants (citral and octanol) were arranged such that relative contributions of the 2 components varied systematically by a factor of 1% (v/v). Odorant concentrations for the target (S+), control (S-), and mixture (S+:S-) odorants were presented relative to threshold for each rat. Rats were initially trained to respond by licking at a spout to obtain liquid reward for either citral or octanol as the reinforced target (S+) odorant. After achieving 100% accuracy, rats were transferred to variable ratio (VR 2) reinforcement for correct responding. Nonreinforced probe trials (2 per block of 22 trials) were tested for each mixture ratio and recorded as either S+ (rats lick-responded in the presence of the mixture) or S- (rats refrained from licking), thereby indicating detection of the trained, S+ odorant. To determine the perceived salience for each ratio, RTs (latency from odorant onset to lick response) were recorded for each trial. Consistent with previous studies, RTs for both odorants were shortest (~150-200ms) when the probe trials consisted of a single, monomolecular component. Binary mixtures that contained as little as 1% of the S-, nontarget odorant, however, were sufficiently different perceptually to increase behavioral RTs (i.e., rats hesitated longer before responding); RTs changed systematically as a function of the binary ratio. Interestingly, the rate of RT change was dependent on which odorant served as the S+, suggesting an asymmetric interaction between the 2 odorants. The data demonstrate the value

  16. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

  17. Binary mixtures of disks and elongated particles: Texture and mechanical properties

    NASA Astrophysics Data System (ADS)

    Azéma, Emilien; Preechawuttipong, Itthichai; Radjai, Farhang

    2016-10-01

    We analyze the shear strength and microstructure of binary granular mixtures consisting of disks and elongated particles by varying systematically both the mixture ratio and degree of homogeneity (from homogeneous to fully segregated). The contact dynamics method is used for numerical simulations with rigid particles interacting by frictional contacts. A counterintuitive finding of this work is that the shear strength, packing fraction, and, at the microscopic scale, the fabric, force, and friction anisotropies of the contact network are all nearly independent of the degree of homogeneity. In other words, homogeneous mixtures have the same strength properties as segregated packings of the two particle shapes. In contrast, the shear strength increases with the proportion of elongated particles correlatively with the increase of the corresponding force and fabric anisotropies. By a detailed analysis of the contact network topology, we show that various contact types contribute differently to force transmission and friction mobilization.

  18. Sedimentation stacking diagram of binary colloidal mixtures and bulk phases in the plane of chemical potentials.

    PubMed

    de las Heras, Daniel; Schmidt, Matthias

    2015-05-20

    We give a full account of a recently proposed theory that explicitly relates the bulk phase diagram of a binary colloidal mixture to its phase stacking phenomenology under gravity (de las Heras and Schmidt 2013 Soft Matter 9 8636). As we demonstrate, the full set of possible phase stacking sequences in sedimentation-diffusion equilibrium originates from straight lines (sedimentation paths) in the chemical potential representation of the bulk phase diagram. From the analysis of various standard topologies of bulk phase diagrams, we conclude that the corresponding sedimentation stacking diagrams can be very rich, even more so when finite sample height is taken into account. We apply the theory to obtain the stacking diagram of a mixture of nonadsorbing polymers and colloids. We also present a catalog of generic phase diagrams in the plane of chemical potentials in order to facilitate the practical application of our concept, which also generalizes to multi-component mixtures.

  19. Viscosity and phase separations of binary CO-He and CO-Ar mixtures

    NASA Astrophysics Data System (ADS)

    Rademacher, N.; Bayarjargal, L.; Morgenroth, W.; Ciezak-Jenkins, J. A.; Winkler, B.

    2015-01-01

    Binary mixtures of 10 and 25 vol% CO in He and 10 vol% CO in Ar have been studied at high pressures and ambient temperature in diamond anvil cells. Phase separations were observed at 5.7(3) GPa, 3.6(2) GPa and 1.6(1) GPa. Earlier studies of ?-He mixtures of comparable concentrations revealed phase separations at significantly larger pressures, while ?-Ar mixtures separate at pressures comparable to those observed in the CO-Ar system here. The viscosity of a CO-rich fluid phase was determined by measuring the velocities of rising He bubbles. After corrections for the influence of the finite container size and of remaining helium in CO, the viscosity of the CO-rich fluid at 3.8(1) GPa was ≈3(1) mPa s, similar to what would be expected for isoelectronic liquid ? under the same conditions.

  20. Dielectric properties of binary mixtures of methyl iso butyl ketone and amino silicone oil

    NASA Astrophysics Data System (ADS)

    Shah, K. N.; Rana, V. A.; Trivedi, C. M.; Vankar, H. P.

    2017-05-01

    Dielectric permittivity ɛ*(ω) = ɛ' - jɛ″ of the binary mixtures of the methyl iso butyl ketone and amino silicone oil in the frequency range 100 Hz to 2 MHz were measured using precision LCR meter at 305.15 K. Relative complex permittivity spectra in the frequency range 100 Hz to 2 MHz, of the mixture solutions of varying concentrations is reported. Determined values of the permittivity at optical frequency of all the samples are also reported. The dielectric parameters are used to gain information about the effect of concentration variation of components of the mixtures on the dielectric properties. It also provides the information about electrode polarization phenomena taking place under the low frequency A.C. electric field.

  1. Neural coding of binary mixtures in a structurally related odorant pair

    PubMed Central

    Cruz, Georgina; Lowe, Graeme

    2013-01-01

    The encoding of odorant mixtures by olfactory sensory neurons depends on molecular interactions at peripheral receptors. However, the pharmacological basis of these interactions is not well defined. Both competitive and noncompetitive mechanisms of receptor binding and activation, or suppression, could contribute to coding. We studied this by analyzing responses of olfactory bulb glomeruli evoked by a pair of structurally related odorants, eugenol (EG) and methyl isoeugenol (MIEG). Fluorescence imaging in synaptopHluorin (spH) mice revealed that EG and MIEG evoked highly overlapped glomerular inputs, increasing the likelihood of mixture interactions. Glomerular responses to binary mixtures of EG and MIEG mostly showed hypoadditive interactions at intermediate and high odorant concentrations, with a few near threshold responses showing hyperadditivity. Dose-response profiles were well fitted by a model of two odorants competitively binding and activating a shared receptor linked to a non-linear transduction cascade. We saw no evidence of non-competitive mechanisms. PMID:23386975

  2. Hydrodynamics and Segregation in Poiseuille Flow of a Binary Granular Mixture

    NASA Astrophysics Data System (ADS)

    Gupta, Ronak; Alam, Meheboob

    2016-11-01

    Steady State profiles of hydrodynamic fields have been computed for the Poiseulle flow of a dilute bi-disperse granular mixture using DSMC (direct simulation Monte Carlo) method. The effects of mass bidispersity and inelasticity are studied and it is found that species segregation follows a non-monotonic trend with increasing mass-ratio if the particles are inelastic. Mixture velocity shows a similar trend. Nonequipartition of granular temperature is expectedly enhanced with increasing mass-ratio and inelasticity, but is additionally a strong function of Knudsen number. Effort is made to compare simulation results with a continuum theory for dilute binary granular mixtures, with the aim being to check if theory is able to predict the novel segregation tendencies uncovered in DSMC simulations.

  3. Concurrent Co2+ and Sr2+ sorption from binary mixtures using aluminum industry waste: Kinetic study

    NASA Astrophysics Data System (ADS)

    Milenković, A.; Smičiklas, I.; Šljivić-Ivanović, M.; Vukelić, N.

    2015-12-01

    Multi-component sorption studies are essential to identify the applicability of red mud as a lowcost sorbent for the simultaneous removal of metal ions from wastewaters. Sorption kinetics of Co2+ and Sr2+ ions was investigated, at different total concentrations of mixtures and different molar ratios of two cations. Kinetics of metal sorption from binary systems was found to be well described by pseudo-second order rate model. Equilibrium sorbed amounts and equilibrium times for Co2+ sorption increased with the increase of its total concentration in the mixture, whereas pseudo-second order rate constants exhibited the opposite trend. Sr2+ sorption was strongly suppressed in the presence of Co2+ ions, and the removal efficiency decreased with increasing concentration and mole fraction of Co2+. Red mud can be used for simultaneous Co2+ and Sr2+ removal from mixtures of lower initial concentration, otherwise Co2+ sorption is dominant.

  4. Kinetics of Order-Disorder Transitions in Binary Mixtures: A Monte Carlo Study

    NASA Astrophysics Data System (ADS)

    Das, Prasenjit; Saha-Dasgupta, Tanusri; Puri, Sanjay

    2016-10-01

    We study ordering kinetics in symmetric and asymmetric binary mixtures, undergoing an order-disorder transition below the critical temperature. We model the microscopic dynamics via an anti-ferromagnetic Ising model with Kawasaki spin-exchange kinetics. This conserves the composition but the order parameter, (staggered magnetization) is not a conserved quantity. The order-parameter correlation function shows dynamical scaling, and the scaling function is independent of mixture composition. The average domain size exhibits power law growth: L(t) ∼ tα. The asymptotic growth regime has α = ½, though there can be prolonged transients with α < ½ for asymmetric mixtures. Our unambiguous observation of the asymptotic universal regime is facilitated by use of an accelerated Monte Carlo technique.

  5. Simulation and theory of fluid fluid interfaces in binary mixtures of hard spheres and hard rods

    NASA Astrophysics Data System (ADS)

    Bolhuis, Peter G.; Brader, Joseph M.; Schmidt, Matthias

    2003-12-01

    We consider the free interface between demixed fluid phases in a mixture of hard spheres and vanishingly thin hard rods using Monte Carlo simulations and density functional theory. Both approaches treat the full binary mixture and hence include all rod-induced many-body depletion interactions between spheres. The agreement between theoretical and simulation results for density and orientation order profiles across the interface is remarkable, even for states not far from the critical point. The simulation results confirm the previously predicted preferred vertical (parallel) alignment of rod orientation to the interface plane at the sphere-rich (sphere-poor) side. This ordering should be experimentally observable in phase-separated colloidal rod-sphere mixtures.

  6. Acute toxicity of binary and ternary mixtures of Cd, Cu, and Zn to Daphnia magna.

    PubMed

    Meyer, Joseph S; Ranville, James F; Pontasch, Mandee; Gorsuch, Joseph W; Adams, William J

    2015-04-01

    Standard static-exposure acute lethality tests were conducted with Daphnia magna neonates exposed to binary or ternary mixtures of Cd, Cu, and Zn in moderately hard reconstituted water that contained 3 mg dissolved organic carbon/L added as Suwannee River fulvic acid. These experiments were conducted to test for additive toxicity (i.e., the response to the mixture can be predicted by combining the responses obtained in single-metal toxicity tests) or nonadditive toxicity (i.e., the response is less than or greater than additive). Based on total metal concentrations (>90% dissolved) the toxicity of the tested metal mixtures could be categorized into all 3 possible additivity categories: less-than-additive toxicity (e.g., Cd-Zn and Cd-Cu-Zn mixtures and Cd-Cu mixtures when Cu was titrated into Cd-containing waters), additive toxicity (e.g., some Cu-Zn mixtures), or more-than-additive toxicity (some Cu-Zn mixtures and Cd-Cu mixtures when Cd was titrated into Cu-containing waters). Exposing the organisms to a range of sublethal to supralethal concentrations of the titrated metal was especially helpful in identifying nonadditive interactions. Geochemical processes (e.g., metal-metal competition for binding to dissolved organic matter and/or the biotic ligand, and possibly supersaturation of exposure waters with the metals in some high-concentration exposures) can explain much of the observed metal-metal interactions. Therefore, bioavailability models that incorporate those geochemical (and possibly some physiological) processes might be able to predict metal mixture toxicity accurately.

  7. 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).

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

    PubMed

    Finotello, Alexia; Bara, Jason E; Narayan, Suguna; Camper, Dean; Noble, Richard D

    2008-02-28

    This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) at 40 degrees C and low pressures (approximately 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % [C2mim][BF4] in [C2mim][Tf2N]. 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 CO2 with N2 or CH4 in pure [C2mim][BF4] can be enhanced by adding 5 mol % [C2mim][Tf2N].

  9. Component information is preserved in glomerular responses to binary odor mixtures in the moth Spodoptera littoralis.

    PubMed

    Carlsson, Mikael A; Chong, Kwok Ying; Daniels, Wiltrud; Hansson, Bill S; Pearce, Tim C

    2007-06-01

    Natural odors are often complex mixtures of different compounds. These mixtures can be perceived to have qualities that are different from their components. Moreover, components can be difficult to distinguish within a blend, even if those components are identifiable when presented individually. Thus, odor components can interact along the olfactory pathway in a nonlinear fashion such that the mixture is not perceived simply as the sum of its components. Here we investigated odor-evoked changes in Ca2+ concentration to binary blends of plant-related substances in individually identified glomeruli in the moth Spodoptera littoralis. We used a wide range of blend ratios and a range of concentrations below the level at which glomerular responses become saturated. We found no statistically significant cases where the mixture response was greater than both component responses at the same total concentration (synergistic interactions) and no statistically significant cases where the mixture response was less than either component presented individually (suppressive interactions). Therefore, we conclude that, for the plant mixtures studied, information of their components is preserved in the neural representations encoded at the first stage of olfactory processing in this moth species.

  10. 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.

  11. Molecular dynamics study of polysaccharides in binary solvent mixtures of an ionic liquid and water.

    PubMed

    Liu, Hanbin; Sale, Kenneth L; Simmons, Blake A; Singh, Seema

    2011-09-01

    Some ionic liquids (ILs) have great promise as effective solvents for biomass pretreatment, and there are several that have been reported that can dissolve large amounts of cellulose. The solubilized cellulose can then be recovered by addition of antisolvents, such as water or ethanol, and this regeneration process plays an important role in the subsequent enzymatic saccharification reactions and in the recovery of the ionic liquid. To date, little is known about the fundamental intermolecular interactions that drive the dissolution and subsequent regeneration of cellulose in complex mixtures of ionic liquids, water, and cellulose. To investigate these interactions, in this work, molecular dynamics (MD) simulations were carried out to study binary and ternary mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) with water and a cellulose oligomer. Simulations of a cellulose oligomer dissolved in three concentrations of binary mixtures of [C2mim][OAc] and water were used to represent the ternary system in the dissolution phase (high [C2mim][OAc] concentration) and present during the initial phase of the regeneration step (intermediate and low [C2mim][OAc] concentrations). The MD analysis of the structure and dynamics that exist in these binary and ternary mixtures provides information on the key intermolecular interactions between cellulose and [C2mim][OAc] that lead to dissolution of cellulose and the key intermolecular interactions in the intermediate states of cellulose precipitation as a function of water content in the cellulose/IL/water system. The analysis of this intermediate state provides new insight into the molecular driving forces present in this ternary system.

  12. The effect of vapor polarity and boiling point on breakthrough for binary mixtures on respirator carbon.

    PubMed

    Robbins, C A; Breysse, P N

    1996-08-01

    This research evaluated the effect of the polarity of a second vapor on the adsorption of a polar and a nonpolar vapor using the Wheeler model. To examine the effect of polarity, it was also necessary to observe the effect of component boiling point. The 1% breakthrough time (1% tb), kinetic adsorption capacity (W(e)), and rate constant (kv) of the Wheeler model were determined for vapor challenges on carbon beds for both p-xylene and pyrrole (referred to as test vapors) individually, and in equimolar binary mixtures with the polar and nonpolar vapors toluene, p-fluorotoluene, o-dichlorobenzene, and p-dichlorobenzene (referred to as probe vapors). Probe vapor polarity (0 to 2.5 Debye) did not systematically alter the 1% tb, W(e), or kv of the test vapors. The 1% tb and W(e) for test vapors in binary mixtures can be estimated reasonably well, using the Wheeler model, from single-vapor data (1% tb +/- 30%, W(e) +/- 20%). The test vapor 1% tb depended mainly on total vapor concentration in both single and binary systems. W(e) was proportional to test vapor fractional molar concentration (mole fraction) in mixtures. The kv for p-xylene was significantly different (p < or = 0.001) when compared according to probe boiling point; however, these differences were apparently of limited importance in estimating 1% tb for the range of boiling points tested (111 to 180 degrees C). Although the polarity and boiling point of chemicals in the range tested are not practically important in predicting 1% tb with the Wheeler model, an effect due to probe boiling point is suggested, and tests with chemicals of more widely ranging boiling point are warranted. Since the 1% tb, and thus, respirator service life, depends mainly on total vapor concentration, these data underscore the importance of taking into account the presence of other vapors when estimating respirator service life for a vapor in a mixture.

  13. Dynamics of glycerine and water transport across human skin from binary mixtures.

    PubMed

    Ventura, S A; Kasting, G B

    2017-04-01

    Skin transport properties of glycerine and water from binary mixtures contacting human skin were determined to better understand the mechanism of skin moisturization by aqueous glycerine formulations. Steady-state permeation for (3) H2 O and (14) C-glycerine across split-thickness human skin in vitro and desorption dynamics of the same permeants in isolated human stratum corneum (HSC) were experimentally determined under near equilibrium conditions. These data were compared to a priori values developed in the context of a thermodynamic model for binary mixtures of glycerine and water and a previously determined water sorption isotherm for HSC. This allowed the estimation of diffusion and partition coefficients for each permeant in the HSC, as well as HSC thickness, as a function of composition of the contacting solution. These data may be used to estimate water retention and associated HSC swelling related to the absorption and slow release of glycerine from the skin. It took 6+ days for glycerine to completely desorb from HSC immersed in glycerine/water binary solutions. Desorption of both (3) H2 O and (14) C-glycerine from HSC was slower in pure water than from binary mixtures, a result that is largely explained by the greater swelling of HSC in water. Parametric relationships were developed for water and glycerine intradiffusivities in HSC as functions of HSC water content, and a mutual diffusion coefficient was estimated by analogy with glycerine/water binary solutions. The intradiffusivity of (14) C-glycerine in HSC as inferred from sorption/desorption experiments was shown to be approximately 10-fold less than that inferred from permeation experiments, whereas the corresponding values for (3) H2 O were comparable. These studies confirm that glycerine enters HSC in substantial quantities and has a long residence time therein. The coupling between bulk water and glycerine transport projected from binary solution data suggests the net effect of glycerine is to

  14. Benzoic Acid and Chlorobenzoic Acids: Thermodynamic Study of the Pure Compounds and Binary Mixtures With Water.

    PubMed

    Reschke, Thomas; Zherikova, Kseniya V; Verevkin, Sergey P; Held, Christoph

    2016-03-01

    Benzoic acid is a model compound for drug substances in pharmaceutical research. Process design requires information about thermodynamic phase behavior of benzoic acid and its mixtures with water and organic solvents. This work addresses phase equilibria that determine stability and solubility. In this work, Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) was used to model the phase behavior of aqueous and organic solutions containing benzoic acid and chlorobenzoic acids. Absolute vapor pressures of benzoic acid and 2-, 3-, and 4-chlorobenzoic acid from literature and from our own measurements were used to determine pure-component PC-SAFT parameters. Two binary interaction parameters between water and/or benzoic acid were used to model vapor-liquid and liquid-liquid equilibria of water and/or benzoic acid between 280 and 413 K. The PC-SAFT parameters and 1 binary interaction parameter were used to model aqueous solubility of the chlorobenzoic acids. Additionally, solubility of benzoic acid in organic solvents was predicted without using binary parameters. All results showed that pure-component parameters for benzoic acid and for the chlorobenzoic acids allowed for satisfying modeling phase equilibria. The modeling approach established in this work is a further step to screen solubility and to predict the whole phase region of mixtures containing pharmaceuticals. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  15. Solubility of anthracene and pyrene in binary alcohol + alcohol solvent mixtures

    SciTech Connect

    Zvaigzne, A.I.; McHale, M.E.R.; Powell, J.R.; Kauppila, A.S.M.; Acree, W.E. Jr.

    1995-11-01

    Solid-liquid equilibrium data of organic nonelectrolyte systems are becoming increasingly important in the petroleum industry, particularly in light of present trends toward heavier feedstocks and known carcinogenicity/mutagenicity of many of the larger polycyclic aromatic compounds. Experimental solubilities are reported for anthracene dissolved in binary 1-octanol + 2-propanol, 2-butanol + 1-butanol, 1-octanol + 1-butanol, 3-methyl-1-butanol + 1-propanol, and 2-methyl-1-propanol + 1-butanol mixtures at 25 C, and for pyrene dissolved in binary solvent mixtures containing 2-ethyl-1-hexanol with 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-octanol, 2-methyl-1-propanol, and 3-methyl-1-butanol at 26 C. Results of these measurements are used to test two mathematical representations based upon the combined nearly ideal binary solvent (NIBS)/Redlich-Kister equation and modified Wilson model. For the 12 systems studied, the combined NIBS/Redlich-Kister equation was found to provide an accurate mathematical representation of the experimental data, with an overall average absolute deviation between measured and calculated values being on the order of 0.4%. Slightly larger deviations were noted in the case of the modified Wilson equation.

  16. Mutual diffusivity in binary mixtures of n-heptane with n-hexane isomers

    SciTech Connect

    Padrel de Oliveira, C.M.; Fareleira, J.M.N.A.; Nieto de Castro, C.A. )

    1989-09-01

    This paper presents a study of the influence of branching in the binary diffusion coefficients of n-heptane + n-hexane isomers, in the liquid state. The measurements have been made with the Taylor dispersion technique, at several compositions, at 283 and 298 K, for the X + n-heptane mixtures, where X = n-hexane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane. The results show a very interesting behavior of the composition dependence of the binary diffusion coefficients, presenting a maximum for compositions about a molar fraction of n-heptane of 0.5, which increases with the increase in the degree of branching, suggesting the possibility of order-disorder effects caused by stereochemically favored packing in the liquid phase and energetically favored segment interaction in the liquid mixtures. An attempt to apply the van der Waals model to these data could not predict the experimental binary diffusion coefficients of these systems within the experimental accuracy.

  17. Quantitative Structure Activity Relationships (QSAR) for Binary Mixtures at Non-Equitoxic Ratios Based on Toxic Ratios-Effects Curves

    PubMed Central

    Tian, Dayong; Lin, Zhifen; Yin, Daqiang

    2013-01-01

    The present study proposed a QSAR model to predict joint effects at non-equitoxic ratios for binary mixtures containing reactive toxicants, cyanogenic compounds and aldehydes. Toxicity of single and binary mixtures was measured by quantifying the decrease in light emission from the Photobacterium phosphoreum for 15 min. The joint effects of binary mixtures (TUsum) can thus be obtained. The results showed that the relationships between toxic ratios of the individual chemicals and their joint effects can be described by normal distribution function. Based on normal distribution equations, the joint effects of binary mixtures at non-equitoxic ratios ( TUsumn:m) can be predicted quantitatively using the joint effects at equitoxic ratios ( TUsum1:1). Combined with a QSAR model of TUsum1:1in our previous work, a novel QSAR model can be proposed to predict the joint effects of mixtures at non-equitoxic ratios ( TUsumn:m). The proposed model has been validated using additional mixtures other than the one used for the development of the model. Predicted and observed results were similar (p>0.05). This study provides an approach to the prediction of joint effects for binary mixtures at non-equitoxic ratios. PMID:23930105

  18. Thermal diffusion segregation in granular binary mixtures described by the Enskog equation

    NASA Astrophysics Data System (ADS)

    Garzó, Vicente

    2011-05-01

    The diffusion induced by a thermal gradient in a granular binary mixture is analyzed here in the context of the (inelastic) Enskog equation. Although the Enskog equation neglects velocity correlations among particles that are about to collide, it retains the spatial correlations arising from volume exclusion effects and thus is expected to be applicable for moderate densities. In the steady state with gradients only along a given direction, a segregation criterion is obtained from the thermal diffusion factor Λ by measuring the amount of segregation parallel to the thermal gradient. As expected, the sign of the factor Λ provides a criterion for the transition between the Brazil-nut effect (BNE) and the reverse Brazil-nut effect (RBNE) by varying the parameters of the mixture (the masses and sizes of particles, concentration, solid volume fraction and coefficients of restitution). The form of the phase diagrams for the BNE/RBNE transition is illustrated in detail for several systems, with special emphasis on the significant role played by the inelasticity of collisions. In particular, an effect already found in dilute gases (segregation in a binary mixture of identical masses and sizes but different coefficients of restitution) is extended to dense systems. A comparison with recent computer simulation results reveals good qualitative agreement at the level of the thermal diffusion factor. The present analysis generalizes to arbitrary concentration previous theoretical results derived in the tracer limit case.

  19. Large attractive depletion interactions in soft repulsive-sphere binary mixtures.

    PubMed

    Cinacchi, Giorgio; Martínez-Ratón, Yuri; Mederos, Luis; Navascués, Guillermo; Tani, Alessandro; Velasco, Enrique

    2007-12-07

    We consider binary mixtures of soft repulsive spherical particles and calculate the depletion interaction between two big spheres mediated by the fluid of small spheres, using different theoretical and simulation methods. The validity of the theoretical approach, a virial expansion in terms of the density of the small spheres, is checked against simulation results. Attention is given to the approach toward the hard-sphere limit and to the effect of density and temperature on the strength of the depletion potential. Our results indicate, surprisingly, that even a modest degree of softness in the pair potential governing the direct interactions between the particles may lead to a significantly more attractive total effective potential for the big spheres than in the hard-sphere case. This might lead to significant differences in phase behavior, structure, and dynamics of a binary mixture of soft repulsive spheres. In particular, a perturbative scheme is applied to predict the phase diagram of an effective system of big spheres interacting via depletion forces for a size ratio of small and big spheres of 0.2; this diagram includes the usual fluid-solid transition but, in the soft-sphere case, the metastable fluid-fluid transition, which is probably absent in hard-sphere mixtures, is close to being stable with respect to direct fluid-solid coexistence. From these results, the interesting possibility arises that, for sufficiently soft repulsive particles, this phase transition could become stable. Possible implications for the phase behavior of real colloidal dispersions are discussed.

  20. An odor interaction model of binary odorant mixtures by a partial differential equation method.

    PubMed

    Yan, Luchun; Liu, Jiemin; Wang, Guihua; Wu, Chuandong

    2014-07-09

    A novel odor interaction model was proposed for binary mixtures of benzene and substituted benzenes by a partial differential equation (PDE) method. Based on the measurement method (tangent-intercept method) of partial molar volume, original parameters of corresponding formulas were reasonably displaced by perceptual measures. By these substitutions, it was possible to relate a mixture's odor intensity to the individual odorant's relative odor activity value (OAV). Several binary mixtures of benzene and substituted benzenes were respectively tested to establish the PDE models. The obtained results showed that the PDE model provided an easily interpretable method relating individual components to their joint odor intensity. Besides, both predictive performance and feasibility of the PDE model were proved well through a series of odor intensity matching tests. If combining the PDE model with portable gas detectors or on-line monitoring systems, olfactory evaluation of odor intensity will be achieved by instruments instead of odor assessors. Many disadvantages (e.g., expense on a fixed number of odor assessors) also will be successfully avoided. Thus, the PDE model is predicted to be helpful to the monitoring and management of odor pollutions.

  1. Novel spectrophotometric methods for simultaneous determination of timolol and dorzolamide in their binary mixture

    NASA Astrophysics Data System (ADS)

    Lotfy, Hayam Mahmoud; Hegazy, Maha A.; Rezk, Mamdouh R.; Omran, Yasmin Rostom

    Two smart and novel spectrophotometric methods namely; absorbance subtraction (AS) and amplitude modulation (AM) were developed and validated for the determination of a binary mixture of timolol maleate (TIM) and dorzolamide hydrochloride (DOR) in presence of benzalkonium chloride without prior separation, using unified regression equation. Additionally, simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of the binary mixture namely; simultaneous ratio subtraction (SRS), ratio difference (RD), ratio subtraction (RS) coupled with extended ratio subtraction (EXRS), constant multiplication method (CM) and mean centering of ratio spectra (MCR). The proposed spectrophotometric procedures do not require any separation steps. Accuracy, precision and linearity ranges of the proposed methods were determined and the specificity was assessed by analyzing synthetic mixtures of both drugs. They were applied to their pharmaceutical formulation and the results obtained were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there is no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

  2. Novel two wavelength spectrophotometric methods for simultaneous determination of binary mixtures with severely overlapping spectra

    NASA Astrophysics Data System (ADS)

    Lotfy, Hayam M.; Saleh, Sarah S.; Hassan, Nagiba Y.; Salem, Hesham

    2015-02-01

    This work presents the application of different spectrophotometric techniques based on two wavelengths for the determination of severely overlapped spectral components in a binary mixture without prior separation. Four novel spectrophotometric methods were developed namely: induced dual wavelength method (IDW), dual wavelength resolution technique (DWRT), advanced amplitude modulation method (AAM) and induced amplitude modulation method (IAM). The results of the novel methods were compared to that of three well-established methods which were: dual wavelength method (DW), Vierordt's method (VD) and bivariate method (BV). The developed methods were applied for the analysis of the binary mixture of hydrocortisone acetate (HCA) and fusidic acid (FSA) formulated as topical cream accompanied by the determination of methyl paraben and propyl paraben present as preservatives. The specificity of the novel methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. No difference was observed between the obtained results when compared to the reported HPLC method, which proved that the developed methods could be alternative to HPLC techniques in quality control laboratories.

  3. Implementation of Ultrasonic Sensing for High Resolution Measurement of Binary Gas Mixture Fractions

    PubMed Central

    Bates, Richard; Battistin, Michele; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Riva, Enrico Da; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

    2014-01-01

    We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10−5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions. PMID:24961217

  4. An Odor Interaction Model of Binary Odorant Mixtures by a Partial Differential Equation Method

    PubMed Central

    Yan, Luchun; Liu, Jiemin; Wang, Guihua; Wu, Chuandong

    2014-01-01

    A novel odor interaction model was proposed for binary mixtures of benzene and substituted benzenes by a partial differential equation (PDE) method. Based on the measurement method (tangent-intercept method) of partial molar volume, original parameters of corresponding formulas were reasonably displaced by perceptual measures. By these substitutions, it was possible to relate a mixture's odor intensity to the individual odorant's relative odor activity value (OAV). Several binary mixtures of benzene and substituted benzenes were respectively tested to establish the PDE models. The obtained results showed that the PDE model provided an easily interpretable method relating individual components to their joint odor intensity. Besides, both predictive performance and feasibility of the PDE model were proved well through a series of odor intensity matching tests. If combining the PDE model with portable gas detectors or on-line monitoring systems, olfactory evaluation of odor intensity will be achieved by instruments instead of odor assessors. Many disadvantages (e.g., expense on a fixed number of odor assessors) also will be successfully avoided. Thus, the PDE model is predicted to be helpful to the monitoring and management of odor pollutions. PMID:25010698

  5. Novel spectrophotometric methods for simultaneous determination of timolol and dorzolamide in their binary mixture.

    PubMed

    Lotfy, Hayam Mahmoud; Hegazy, Maha A; Rezk, Mamdouh R; Omran, Yasmin Rostom

    2014-05-21

    Two smart and novel spectrophotometric methods namely; absorbance subtraction (AS) and amplitude modulation (AM) were developed and validated for the determination of a binary mixture of timolol maleate (TIM) and dorzolamide hydrochloride (DOR) in presence of benzalkonium chloride without prior separation, using unified regression equation. Additionally, simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of the binary mixture namely; simultaneous ratio subtraction (SRS), ratio difference (RD), ratio subtraction (RS) coupled with extended ratio subtraction (EXRS), constant multiplication method (CM) and mean centering of ratio spectra (MCR). The proposed spectrophotometric procedures do not require any separation steps. Accuracy, precision and linearity ranges of the proposed methods were determined and the specificity was assessed by analyzing synthetic mixtures of both drugs. They were applied to their pharmaceutical formulation and the results obtained were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there is no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

  6. Novel two wavelength spectrophotometric methods for simultaneous determination of binary mixtures with severely overlapping spectra.

    PubMed

    Lotfy, Hayam M; Saleh, Sarah S; Hassan, Nagiba Y; Salem, Hesham

    2015-02-05

    This work presents the application of different spectrophotometric techniques based on two wavelengths for the determination of severely overlapped spectral components in a binary mixture without prior separation. Four novel spectrophotometric methods were developed namely: induced dual wavelength method (IDW), dual wavelength resolution technique (DWRT), advanced amplitude modulation method (AAM) and induced amplitude modulation method (IAM). The results of the novel methods were compared to that of three well-established methods which were: dual wavelength method (DW), Vierordt's method (VD) and bivariate method (BV). The developed methods were applied for the analysis of the binary mixture of hydrocortisone acetate (HCA) and fusidic acid (FSA) formulated as topical cream accompanied by the determination of methyl paraben and propyl paraben present as preservatives. The specificity of the novel methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. No difference was observed between the obtained results when compared to the reported HPLC method, which proved that the developed methods could be alternative to HPLC techniques in quality control laboratories.

  7. Toxicity of binary mixtures of oil fractions to sea urchin embryos.

    PubMed

    Rial, Diego; Vázquez, José A; Menduiña, Araceli; García, Ana M; González, M Pilar; Mirón, Jesús; Murado, Miguel A

    2013-12-15

    The assumption of additive toxicity for oil compounds is related to a narcotic mode of action. However, the joint toxicity of oil fractions has not been fully investigated. A fractionation of Maya crude oil into aliphatics, aromatics and polars was performed, fractions were dissolved in dimethyl sulfoxide (DMSO) and subsequently toxicity of single fractions and binary mixtures was assessed using the sea urchin embryo test. The descriptive ability of Concentration Addition (CA), Independent Action (IA) and modifications of both models for describing the joint toxicity of mixtures has also been evaluated. The hydrocarbon content extractable with dichloromethane of the fractions dissolved in DMSO was: 12.0 ± 1.8 mg mL(-1), 39.0 ± 0.5 mg mL(-1) and 20.5 ± 2.5 mg mL(-1) for aliphatics, aromatics and polars, respectively. The toxicity of the extracts in DMSO of the fractions as EC50 (μLL(-1)) was: aliphatics (165.8-242.3)binary mixtures (aliphatics-aromatics, aromatics-polars) greater than the IA (aliphatics-polars) according to the Akaike Information Criterion, so CA was considered a better option than IA to explain the joint toxicity of oil fractions. In addition, synergistic or antagonistic effects were not observed.

  8. Simplified Gradient Theory Modeling of the Surface Tension for Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Lin, H.; Duan, Y. Y.; Zhang, J. T.

    2008-02-01

    In this work, the gradient theory was combined with the volume translation Peng-Robinson and Soave Redlich-Kwong equations of state (VTPR and VTSRK EOSs) and the influence parameter correlation to predict the surface tension of binary mixtures. The density profiles of mixtures across the interface were assumed to be linearly distributed to simplify the gradient theory model. The only two inputs of the theory are the Helmholtz free-energy density of the homogeneous fluid and the influence parameter of the inhomogeneous fluid. The VTPR and VTSRK equations of state were applied to determine the Helmholtz free-energy density and the bulk properties. The influence parameter of the inhomogeneous fluid was calculated from a correlation published previously (Lin et al. Fluid Phase Equilib 254:75, 2007). The only adjustable coefficient of the simplified gradient theory was set equal to zero, which made the theory predictive. The surface tension predicted by this model shows good agreement with experimental data for binary non-polar and polar mixtures.

  9. Binary mixtures of neonicotinoids show different transcriptional changes than single neonicotinoids in honeybees (Apis mellifera).

    PubMed

    Christen, Verena; Bachofer, Sara; Fent, Karl

    2017-01-01

    Among the many factors responsible for the decline of bee populations are plant protection products such as neonicotinoids. In general, bees are exposed to not only one but mixtures of such chemicals. At environmental realistic concentrations neonicotinoids may display negative effects on the immune system, foraging activity, learning and memory formation of bees. Neonicotinoids induce alterations of gene transcripts such as nicotinic acetylcholine receptor (nAChR) subunits, vitellogenin, genes of the immune system and genes linked to memory formation. While previous studies focused on individual compounds, the effect of neonicotinoid mixtures in bees is poorly known. Here we investigated the effects of neonicotinoids acetamiprid, clothianidin, imidacloprid and thiamethoxam as single compounds, and binary mixtures thereof in honeybees. We determined transcriptional changes of nAChR subunits and vitellogenin in the brain of experimentally exposed honeybees after exposure up to 72 h. Exposure concentrations were selected on the basis of lowest effect concentrations of the single compounds. Transcriptional induction of nAChRs and vitellogenin was strongest for thiamethoxam, and weakest for acetamiprid. To a large extent, binary mixtures did not show additive transcriptional inductions but they were less than additive. Our data suggest that the joint transcriptional activity of neonicotinoids cannot be explained by concentration addition. The in vivo effects are not only governed by agonistic interaction with nAChRs alone, but are more complex as a result of interactions with other pathways as well. Further studies are needed to investigate the physiological joint effects of mixtures of neonicotinoids and other plant protection products on bees to better understand their joint effects.

  10. Optimizing the surface density of polyethylene glycol chains by grafting from binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Arcot, Lokanathan; Ogaki, Ryosuke; Zhang, Shuai; Meyer, Rikke L.; Kingshott, Peter

    2015-06-01

    Polyethylene glycol (PEG) brushes are very effective at controlling non-specific deposition of biological material onto surfaces, which is of paramount importance to obtaining successful outcomes in biomaterials, tissue engineered scaffolds, biosensors, filtration membranes and drug delivery devices. We report on a simple 'grafting to' approach involving binary solvent mixtures that are chosen based on Hansen's solubility parameters to optimize the solubility of PEG thereby enabling control over the graft density. The PEG thiol-gold model system enabled a thorough characterization of PEG films formed, while studies on a PEG silane-silicon system examined the versatility to be applied to any substrate-head group system by choosing an appropriate solvent pair. The ability of PEG films to resist non-specific adsorption of proteins was quantitatively assessed by full serum exposure studies and the binary solvent strategy was found to produce PEG films with optimal graft density to efficiently resist protein adsorption.

  11. Configuration-specific kinetic theory applied to an ideal binary gas mixture.

    PubMed

    Wiseman, Floyd L

    2006-10-05

    This paper is the second in a two-part series dealing with the configuration-specific analyses for molecular collision events of hard, spherical molecules at thermal equilibrium. The first paper analyzed a single-component system, and the reader is referred to it for the fundamental concepts. In this paper, the expressions for the configuration-specific collision frequencies and the average line-of-centers collision angles and speeds are derived for an ideal binary gas mixture. The analyses show that the average line-of-centers quantities are all dependent upon the ratio of the masses of the two components, but not upon molecular size. Of course, the configuration-specific collision frequencies do depend on molecular size. The expression for the overall binary collision frequency is a simple sum of the configuration-specific collision frequencies and is identical to the conventional expression.

  12. Solid-liquid equilibria for binary mixtures composed of acenaphthene, dibenzofuran, fluorene, phenanthrene, and diphenylmethane

    SciTech Connect

    Lee, M.J.; Chen, C.H.; Lin, H.

    1999-09-01

    The liquidus lines were determined with a solid-disappearance method for binary mixtures composed of acenaphthene, dibenzofuran, fluorene, phenanthrene, and diphenylmethane. While the first four substances are model compounds of wash oil, which has widely been used as a solvent to remove aromatics from coal oven gas, diphenylmethane is a high-boiling and low-melting compound that is a potential additive to modify the performance of wash oil. Each of the seven binaries appears to be a simple eutectic system, as evidenced by the experimental results. The Wilson and the NRTL models were employed to correlate the solid-liquid equilibrium data. Both activity coefficient models were found to represent accurately the nonideality of the liquid-phase for the investigated systems.

  13. Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids

    NASA Astrophysics Data System (ADS)

    Lauerer, Alexander; Binder, Tomas; Chmelik, Christian; Miersemann, Erich; Haase, Jürgen; Ruthven, Douglas M.; Kärger, Jörg

    2015-07-01

    Under certain conditions, during binary mixture adsorption in nanoporous hosts, the concentration of one component may temporarily exceed its equilibrium value. This implies that, in contrast to Fick's Law, molecules must diffuse in the direction of increasing rather than decreasing concentration. Although this phenomenon of `overshooting' has been observed previously, it is only recently, using microimaging techniques, that diffusive fluxes in the interior of nanoporous materials have become accessible to direct observation. Here we report the application of interference microscopy to monitor `uphill' fluxes, covering the entire period of overshooting from initiation until final equilibration. It is shown that the evolution of the profiles can be adequately predicted from the single-component diffusivities together with the binary adsorption equilibrium data. The guest molecules studied (carbon dioxide, ethane and propene) and the host material (ZSM-58 or DDR) are of practical interest in relation to the development of kinetically selective adsorption separation processes.

  14. Flow regime and deposition pattern of evaporating binary mixture droplet suspended with particles.

    PubMed

    Zhong, Xin; Duan, Fei

    2016-02-01

    The flow regimes and the deposition pattern have been investigated by changing the ethanol concentration in a water-based binary mixture droplet suspended with alumina nanoparticles. To visualize the flow patterns, Particle Image Velocimetry (PIV) has been applied in the binary liquid droplet containing the fluorescent microspheres. Three distinct flow regimes have been revealed in the evaporation. In Regime I, the vortices and chaotic flows are found to carry the particles to the liquid-vapor interface and to promote the formation of particle aggregation. The aggregates move inwards in Regime II as induced by the Marangoni flow along the droplet free surface. Regime III is dominated by the drying of the left water and the capillary flow driving particles radially outward is observed. The relative weightings of Regimes I and II, which are enhanced with an increasing load of ethanol, determine the motion of the nanoparticles and the formation of the final drying pattern.

  15. Orientational ordering and phase behaviour of binary mixtures of hard spheres and hard spherocylinders.

    PubMed

    Wu, Liang; Malijevský, Alexandr; Jackson, George; Müller, Erich A; Avendaño, Carlos

    2015-07-28

    We study the structure and fluid-phase behaviour of binary mixtures of hard spheres (HSs) and hard spherocylinders (HSCs) in isotropic and nematic states using the NPnAT ensemble Monte Carlo (MC) approach in which the normal component of the pressure tensor is fixed in a system confined between two hard walls. The method allows one to estimate the location of the isotropic-nematic phase transition and to observe the asymmetry in the composition between the coexisting phases, with the expected enhancement of the HSC concentration in the nematic phase. This is in stark contrast with the previously reported MC simulations where a conventional isotropic NPT ensemble was used. We further compare the simulation results with the theoretical predictions of two analytic theories that extend the original Parsons-Lee theory using the one-fluid and the many-fluid approximations [Malijevský et al., J. Chem. Phys. 129, 144504 (2008)]. In the one-fluid version of the theory, the properties of the mixture are related to an effective one-component HS system, while in the many-fluid theory, the components of the mixtures are represented as separate effective HS particles. The comparison reveals that both the one- and the many-fluid approaches provide a reasonably accurate quantitative description of the mixture including the predictions of the isotropic-nematic phase boundary and degree of orientational order of the HSC-HS mixture.

  16. Thermodiffusion, molecular diffusion and Soret coefficients of aromatic+n-alkane binary mixtures

    NASA Astrophysics Data System (ADS)

    Larrañaga, Miren; Bou-Ali, M. Mounir; Lapeira, Estela; Lizarraga, Ion; Santamaría, Carlos

    2016-10-01

    In the present work, we have measured the thermodiffusion coefficient of 51 binary liquid mixtures at 25 oC. These mixtures correspond to the series of the aromatics toluene and 1-methylnaphthalene with n-alkanes nCi (i = 6, 8, 10, 12, and 14) at different mass fractions in the whole range. For that, we have used the thermogravitational technique. It is shown that the thermodiffusion coefficient is a linear function of the mass fraction in all the mixtures. Extrapolating the lines, we obtain the thermodiffusion coefficient in dilute solutions of n-alkanes for both toluene and 1-methylnaphthalene. These limiting values show a linear dependence with the inverse of the product of the molecular weights. In addition, we have measured the molecular diffusion coefficient of all the mixtures at 0.5 of mass fraction and at 25 oC, by the sliding symmetric tubes technique. It is observed that the product of this coefficient with the viscosity at the same concentrations takes a constant value for each of the series considered. Finally, we have also determined the Soret coefficient of the equimass mixtures by the combination of the measurements of thermodiffusion and molecular diffusion coefficients.

  17. Quantitative Characterization of the Toxicities of Cd-Ni and Cd-Cr Binary Mixtures Using Combination Index Method

    PubMed Central

    Zheng, Minyi; Qin, Meng; Zhang, Xin; Zeng, Honghu; Liang, Yanpeng

    2016-01-01

    Direct equipartition ray design was used to construct Cd-Ni and Cd-Cr binary mixtures. Microplate toxicity analysis was used to evaluate the toxicity of individual substance and the Cd-Ni and Cd-Cr mixtures on Chlorella pyrenoidosa and Selenastrum capricornutum. The interacting toxicity of the mixture was analyzed with concentration addition (CA) model. In addition, combination index method (CI) was proposed and used to quantitatively characterize the toxicity of the binary mixtures of Cd-Ni and Cd-Cr observed in experiment and find the degree of deviation from the predicted outcome of the CA model, that is, the intensity of interacting toxicity. Results indicate that most of the 20 binary mixtures exhibit enhancing and synergistic effect, and only Cd-Cr-R4 and Cd-Cr-R5 mixtures have relatively high antagonistic effects against C. pyrenoidosa. Based on confidence interval, CI can compare the intensities of interaction of the mixtures under varying levels of effect. The characterization methods are applicable for analyzing binary mixture with complex interaction. PMID:28044127

  18. Synergistic toxicity and physiological impact of imidacloprid alone and binary mixtures with seven representative pesticides on honey bee (Apis mellifera)

    USDA-ARS?s Scientific Manuscript database

    Imidacloprid is the most widely used insecticide in the world. In this study, we used spraying methods to simulate field exposures of bees to formulated imidacloprid (Advise® 2FL) alone and binary mixtures with seven pesticides from different classes. Synergistic toxicity was detected from mixtures ...

  19. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1988-06-28

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  20. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, Loucas G.; Hunter, Scott R.

    1990-01-01

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

  1. Quantitative Characterization of the Toxicities of Cd-Ni and Cd-Cr Binary Mixtures Using Combination Index Method.

    PubMed

    Mo, Lingyun; Zheng, Minyi; Qin, Meng; Zhang, Xin; Liu, Jie; Qin, Litang; Zeng, Honghu; Liang, Yanpeng

    2016-01-01

    Direct equipartition ray design was used to construct Cd-Ni and Cd-Cr binary mixtures. Microplate toxicity analysis was used to evaluate the toxicity of individual substance and the Cd-Ni and Cd-Cr mixtures on Chlorella pyrenoidosa and Selenastrum capricornutum. The interacting toxicity of the mixture was analyzed with concentration addition (CA) model. In addition, combination index method (CI) was proposed and used to quantitatively characterize the toxicity of the binary mixtures of Cd-Ni and Cd-Cr observed in experiment and find the degree of deviation from the predicted outcome of the CA model, that is, the intensity of interacting toxicity. Results indicate that most of the 20 binary mixtures exhibit enhancing and synergistic effect, and only Cd-Cr-R4 and Cd-Cr-R5 mixtures have relatively high antagonistic effects against C. pyrenoidosa. Based on confidence interval, CI can compare the intensities of interaction of the mixtures under varying levels of effect. The characterization methods are applicable for analyzing binary mixture with complex interaction.

  2. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1990-06-26

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  3. Toxicity of binary mixtures of metal oxide nanoparticles to Nitrosomonas europaea.

    PubMed

    Yu, Ran; Wu, Junkang; Liu, Meiting; Zhu, Guangcan; Chen, Lianghui; Chang, Yan; Lu, Huijie

    2016-06-01

    Although the widely used metal oxide nanoparticles (NPs) titanium dioxide NPs (n-TiO2), cerium dioxide NPs (n-CeO2), and zinc oxide NPs (n-ZnO) have been well known for their potential cytotoxicities to environmental organisms, their combined effects have seldom been investigated. In this study, the short-term binary effect of n-CeO2 and n-TiO2 or n-ZnO on a model ammonia oxidizing bacterium, Nitrosomonas europaea were evaluated based on the examinations of cells' physiological, metabolic, and transcriptional responses. The addition of n-TiO2 mitigated the negative effect of more toxic n-CeO2 and the binary toxicity (antagonistic toxicity) of n-TiO2 and n-CeO2 was generally lower than the single NPs induced one. While the n-CeO2/n-ZnO mixture exerted higher cytotoxicity (synergistic cytotoxicity) than that from single NPs. The increased addition of the less toxic n-CeO2 exaggerated the binary toxicity of n-CeO2/n-ZnO mixture although the solubility of n-ZnO was not significantly affected, which excluded the contribution of the dissolved Zn ions to the enhancement of the combined cytotoxicity. The cell membrane disturbances and NP internalizations were detected for all the NP impacted cultures and the electrostatic interactions among the two distinct NPs and the cells were expected to play a key role in mediating their direct contacts and the eventual binary nanotoxicity to the cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Unexpected toxic interactions in the freshwater amphipod Gammarus pulex (L.) exposed to binary copper and nickel mixtures.

    PubMed

    Charles, Jérémie; Crini, Grégorio; Degiorgi, François; Sancey, Bertrand; Morin-Crini, Nadia; Badot, Pierre-Marie

    2014-01-01

    To document the toxicity of copper and nickel in binary mixtures, freshwater amphipods Gammarus pulex were exposed to the metals given independently or as mixtures. Toxicity to Cu alone was relatively high: 96-h LC10 and LC50 were found at 91 and 196 μg L(-1), respectively. Toxicity to Ni alone was very low, with 96-h LC10 and LC50 of 44,900 and 79,200 μg L(-1), respectively. Mixture toxicities were calculated from single toxicity data using conventional models. Modeled toxicity was then compared with the measured toxicity of the binary mixture. Two kinds of mixtures were tested. Type I mixtures were designed as combinations of Cu and Ni given at the same effect concentrations, when taken independently, to identify possible interactions between copper and nickel. In type II mixtures, Cu concentrations varied from 0 to 600 μg L(-1) while the nickel concentration was kept constant at 500 μg L(-1) to mimic conditions of industrial wastewater discharges. Ni and Cu showed synergic effects in type I mixtures while type II mixtures revealed antagonistic effects. Low doses of Ni reduced Cu toxicity towards G. pulex. These results show that even for simple binary mixtures of contaminants with known chemistry and toxicity, unexpected interactions between the contaminants may occur. This reduces the reliability of conventional additivity models.

  5. Picosecond solvation dynamics—A potential viewer of DMSO—Water binary mixtures

    SciTech Connect

    Banik, Debasis; Kundu, Niloy; Kuchlyan, Jagannath; Roy, Arpita; Banerjee, Chiranjib; Ghosh, Surajit; Sarkar, Nilmoni

    2015-02-07

    In this work, we have investigated the composition dependent anomalous behavior of dimethyl sulfoxide (DMSO)-water binary mixture by collecting the ultrafast solvent relaxation response around a well known solvation probe Coumarin 480 (C480) by using a femtosecond fluorescence up-conversion spectrometer. Recent molecular dynamics simulations have predicted two anomalous regions of DMSO-water binary mixture. Particularly, these studies encourage us to investigate the anomalies from experimental background. DMSO-water binary mixture has repeatedly given evidences of its dual anomalous nature in front of our systematic investigation through steady-state and time-resolved measurements. We have calculated average solvation times of C480 by two individual well-known methods, among them first one is spectral-reconstruction method and another one is single-wavelength measurement method. The results of both the methods roughly indicate that solvation time of C480 reaches maxima in the mole fraction of DMSO X{sub D} = 0.12–0.17 and X{sub D} = 0.27–0.35, respectively. Among them, the second region (X{sub D} = 0.27–0.35) is very common as most of the thermodynamic properties exhibit deviation in this range. Most probably, the anomalous solvation trend in this region is fully guided by the shear viscosity of the medium. However, the first region is the most interesting one. In this region due to formation of strongly hydrogen bonded 1DMSO:2H{sub 2}O complexes, hydration around the probe C480 decreases, as a result of which solvation time increases.

  6. Modeling counterion binding in ionic-nonionic and ionic-zwitterionic binary surfactant mixtures.

    PubMed

    Goldsipe, Arthur; Blankschtein, Daniel

    2005-10-25

    A predictive molecular-thermodynamic theory is developed to model the effect of counterion binding on micellar solution properties of binary surfactant mixtures of ionic and nonionic (or zwitterionic) surfactants. The theory combines a molecular-thermodynamic description of micellization in binary surfactant mixtures with a recently developed model of counterion binding to single-component ionic surfactant micelles. The thermodynamic component of the theory models the equilibrium between the surfactant monomers, the counterions, and the mixed micelles. The molecular component of the theory models the various contributions to the free-energy change associated with forming a mixed micelle from ionic surfactants, nonionic (or zwitterionic) surfactants, and bound counterions (referred to as the free energy of mixed micellization). Specifically, the various molecular contributions to the free energy of mixed micellization model the underlying physics associated with the assembly of, and the interactions between, the surfactant polar heads, the surfactant nonpolar tails, and the bound counterions. Utilizing known structural characteristics of the surfactants and the counterions, along with the solution conditions, the free energy of mixed micellization is minimized to predict various optimal micelle characteristics, including the degree of counterion binding, the micelle composition, and the micelle shape and size. These predicted optimal micelle characteristics are then used to predict the critical micelle concentration (cmc) and the average micelle aggregation number. Our predictions of the degree of counterion binding, the cmc, and the average micelle aggregation number show good agreement with available experimental results from the literature for several binary surfactant mixtures. In addition, the theory is used to shed light on the relationship between the micelle composition, counterion binding and ion condensation, and the micelle shape transition.

  7. Axial segregation of horizontally vibrated binary granular mixtures in an offset-Christmas tree channel

    NASA Astrophysics Data System (ADS)

    Bhateja, Ashish; Sharma, Ishan; Singh, Jayant K.

    2013-06-01

    We investigate segregation in a horizontally vibrated binary granular mixture in a closed offset-Christmas tree channel. The segregation phenomenon occurs in two steps: vertical sorting followed by axial segregation. In the first step, sorting occurs via Brazil-nut effect or reverse Brazil-nut effect depending on the particles' size and density ratios. The two layers thus formed then separate axially towards opposite-ends of the channel with the top layer always moving towards root of the Christmas tree. We discuss the segregation mechanism responsible for axial segregation.

  8. Demixing can occur in binary hard-sphere mixtures with negative nonadditivity.

    PubMed

    Santos, A; López de Haro, M

    2005-07-01

    A binary fluid mixture of nonadditive hard spheres characterized by a size ratio gamma = sigma(2)/sigma(1) < 1 and a nonadditivity parameter Delta = 2 sigma(12)/(sigma(1) + sigma(2)) - 1 is considered in infinitely many dimensions. From the equation of state in the second virial approximation (which is exact in the limit d--> infinity) a demixing transition with a critical consolute point at a packing fraction scaling as eta approximately d2(-d) is found, even for slightly negative nonadditivity, if Delta >-1/8 (ln gamma)(2). Arguments concerning the stability of the demixing with respect to freezing are provided.

  9. Binary rototranslational hyper-Rayleigh spectra of H(2)-He gas mixture.

    PubMed

    Godet, J-L; Bancewicz, T; Głaz, W; Maroulis, G; Haskopoulos, A

    2009-11-28

    The collision-induced rototranslational hyper-Rayleigh spectra of gaseous H(2)-He mixture are computed and discussed in the binary regime. As the input data we use our ab initio computed H(2)-He collision-induced first dipole hyperpolarizability tensor Deltabeta(R). Both the vector and the septor part of the H(2)-He hyper-Rayleigh spectra are evaluated at room temperature (T=295 K). The spectra are calculated assuming the full quantum computations based on the Schrödinger equation of the relative translational motion in the isotropic H(2)-He potential as well as using semiclassical methods.

  10. Tuning the electronic environment of the anion by using binary ionic liquid mixtures

    NASA Astrophysics Data System (ADS)

    Men, Shuang; Licence, Peter

    2017-08-01

    The electronic environment of the anion is tuned by using binary ionic liquid mixtures employing a common anion and two cations with large difference in acidity. X-ray photoelectron spectroscopy is used to monitor the change of the electronic environment of the anion by measuring the binding energy of elements present in the anion. It is found that due to the large difference in acidity of the two cations, noticeable shifts can be observed for all anion-based components, no matter how basic the anion is.

  11. The susceptibility critical exponent for a nonaqueous ionic binary mixture near a consolute point

    NASA Technical Reports Server (NTRS)

    Zhang, Kai C.; Briggs, Matthew E.; Gammon, Robert W.; Levelt Sengers, J. M. H.

    1992-01-01

    We report turbidity measurements of a nonaqueous ionic solution of triethyl n-hexylammonium triethyl n-hexylboride in diphenyl ether. A classical susceptibility critical exponent gamma = 1.01 +/- 0.01 is obtained over the reduced temperature range t between values of 0.1 and 0.0001. The best fits of the sample transmission had a standard deviation of 0.39 percent over this range. Ising and spherical model critical exponents are firmly excluded. The correlation length amplitude xi sub 0 from fitting is 1.0 +/- 0.2 nm which is much larger than values found in neutral fluids and some aqueous binary mixtures.

  12. Universal amplitude ratios and the interfacial tension near consolute points of binary liquid mixtures

    NASA Technical Reports Server (NTRS)

    Moldover, M. R.; Schmidt, J. W.; Chaar, H.

    1986-01-01

    The interfacial tension of the binary liquid mixtures triethylamine/heavy water, triethylamine/water, and cyclohexane/methanol near their consolute temperatures is determined experimentally by measuring the densities of the phases and the capillary lengths. The results are presented in tables and graphs and compared with published data obtained by other methods and with theoretical predictions. The findings are shown to be in good agreement with previous experiments, confirming the discrepancy between temperature-independent universal amplitude ratios calculated from such data and those predicted by renormalization-group calculations or Monte Carlo simulations of Ising models.

  13. Experimental and Predicted Viscosities of Binary Mixtures Containing Chlorinated and Oxygenated Compounds

    NASA Astrophysics Data System (ADS)

    Montaño, D.; Artigas, H.; Royo, F. M.; Lafuente, Carlos

    2013-01-01

    This study presents the viscosities, both kinematic and dynamic, of binary mixtures of 1-chlorobutane, 2-chlorobutane, or 1-chloro-2-methylpropane with butyl ethyl ether or methyl tert-butyl ether from T = 283.15 K to T = 313.15 K at atmospheric pressure as a function of composition. Kinematics viscosities were measured using an Ubbelohde viscometer. The dynamic viscosities were obtained from experimental kinematic viscosities and previously reported density data. The viscosity results have been employed to check the reliability of the Wu-UNIFAC method.

  14. Dielectric Properties of KNO3-NH4NO3 Crystalline Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Milinskii, A. Yu.

    2016-01-01

    The temperature dependences of linear and nonlinear dielectric properties of potassium nitrate (KNO3) and crystalline binary mixtures (KNO3)1-x(NH4NO3)x (x = 0.025, 0.035, 0.05, 0.1) in the temperature interval 300-460 K have been investigated. An influence of the NH4NO3 impurity on the existence interval of the ferroelectric phase with increase of the impurity content has been detected. For x = 0.05 the ferroelectric phase is maintained down to room temperature.

  15. Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface

    SciTech Connect

    Ritter, J.A.

    1992-10-01

    Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry`s Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

  16. Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface

    SciTech Connect

    Ritter, J.A.

    1992-01-01

    Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry's Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

  17. The susceptibility critical exponent for a nonaqueous ionic binary mixture near a consolute point

    NASA Technical Reports Server (NTRS)

    Zhang, Kai C.; Briggs, Matthew E.; Gammon, Robert W.; Levelt Sengers, J. M. H.

    1992-01-01

    We report turbidity measurements of a nonaqueous ionic solution of triethyl n-hexylammonium triethyl n-hexylboride in diphenyl ether. A classical susceptibility critical exponent gamma = 1.01 +/- 0.01 is obtained over the reduced temperature range t between values of 0.1 and 0.0001. The best fits of the sample transmission had a standard deviation of 0.39 percent over this range. Ising and spherical model critical exponents are firmly excluded. The correlation length amplitude xi sub 0 from fitting is 1.0 +/- 0.2 nm which is much larger than values found in neutral fluids and some aqueous binary mixtures.

  18. Smectic-C* alpha-smectic-C* Phase Transition and Critical Point in Binary Mixtures

    SciTech Connect

    Liu,Z.; Wang, S.; McCoy, B.; Cady, A.; Pindak, R.; Caliebe, W.; Takekoshi, K.; Ema, K.; Nguyen, H.; Huang, C.

    2006-01-01

    We have investigated the smectic-C*{sub {alpha}}-smectic-C* (SmC*{sub {alpha}}-SmC*) transition in a series of binary mixtures with resonant x-ray diffraction, differential optical reflectivity, and heat capacity measurements. Results show that the phases are separated by a first-order transition that ends at a critical point. We report the observation of such a critical point. We have proposed the appropriate order parameter and obtained values of two critical exponents associated with this transition. The values of the critical exponents suggest that long-range intersections are present in the SmC*{sub {alpha}}-SmC* critical regions.

  19. Different spectrophotometric methods applied for the analysis of binary mixture of flucloxacillin and amoxicillin: A comparative study.

    PubMed

    Attia, Khalid A M; Nassar, Mohammed W I; El-Zeiny, Mohamed B; Serag, Ahmed

    2016-05-15

    Three different spectrophotometric methods were applied for the quantitative analysis of flucloxacillin and amoxicillin in their binary mixture, namely, ratio subtraction, absorbance subtraction and amplitude modulation. A comparative study was done listing the advantages and the disadvantages of each method. All the methods were validated according to the ICH guidelines and the obtained accuracy, precision and repeatability were found to be within the acceptable limits. The selectivity of the proposed methods was tested using laboratory prepared mixtures and assessed by applying the standard addition technique. So, they can be used for the routine analysis of flucloxacillin and amoxicillin in their binary mixtures.

  20. Fundamental measure density functional theory studies on the freezing of binary hard-sphere and Lennard-Jones mixtures

    SciTech Connect

    Warshavsky, Vadim B.; Song, Xueyu

    2008-07-18

    Free energies and correlation functions of liquid and solid hard-sphere (HS) mixtures are calculated using the fundamental measure density functional theory. Using the thermodynamic perturbation theory the free energies of solid and liquid Lennard-Jones (LJ) mixtures are obtained from correlation functions of HS systems within a single theoretical approach. The resulting azeotrope- and spindle-type solid-liquid phase diagrams of HS and LJ binary mixtures are in good agreement with the corresponding ones from computer simulations.

  1. Wetting layers caused by surface ionization in a near-critical binary liquid mixture

    NASA Astrophysics Data System (ADS)

    Ripple, Dean; Wu, Xiao-Lun; Franck, Carl

    1988-11-01

    Kayser [Phys. Rev. Lett. 56, 1831 (1986)] has proposed that surface ionization provides the long-range force responsible for the wetting layers seen in the binary liquid mixture CS2+CH3NO2 on borosilicate glass substrates. We use scaling theory to find the equation of state for the near-critical mixtures, and then derive a free-energy functional for the wetting layer that incorporates surface ionization forces. This model includes critical adsorption effects and is well suited for calculations of wetting layers in the single-phase region. Within the uncertainties of the material properties, reflectivities of the glass-liquid interface derived from the theoretical concentration profiles do agree with experimental reflectivity values for wetting layers in the one-phase region. We confirm that surface ionization produces the dominant long-range force in CS2+CH3NO2 on glass.

  2. Surface segregation in binary mixtures of imidazolium-based ionic liquids

    NASA Astrophysics Data System (ADS)

    Souda, Ryutaro

    2010-09-01

    Surface composition of binary mixtures of room-temperature ionic liquids has been investigated using time-of-flight secondary ion mass spectrometry at room temperature over a wide composition range. The imidazolium cations with longer aliphatic groups tend to segregate to the surface, and a bis(trifluoromethanesulfonyl)imide anion (Tf 2N -) is enriched at the surface relative to hexafluorophosphate (PF 6-). The surface of an equimolar mixture of Li[Tf 2N] and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]) has a nominal composition of [bmim][Tf 2N] because of surface segregation and ligand exchange. The surface segregation of cations and anions is likely to result from alignment of specific ligand-exchanged molecules at the topmost surface layer to exclude more hydrophobic part of the molecules.

  3. Separation of binary granular mixtures under vibration and differential magnetic levitation force.

    PubMed

    Catherall, A T; López-Alcaraz, P; Sánchez, P; Swift, Michael R; King, P J

    2005-02-01

    The application of both a strong magnetic field and a magnetic field gradient to a diamagnetic or paramagnetic material can produce a vertical force that acts in concert with the force of gravity. We consider a binary granular mixture in which the two components have different magnetic susceptibilities and therefore experience different effective forces of gravity when subjected to an inhomogeneous magnetic field. Under vertical vibration, such a mixture may rapidly separate into regions almost pure in the two components. We investigate the conditions for this behavior, studying the speed and completeness of separation as a function of differential effective gravity and the frequency and amplitude of vibration. The influence of the cohesive magnetic dipole-dipole interactions on the separation process is also investigated. In our studies insight is gained through the use of a molecular dynamics simulation model.

  4. Dissipative particle dynamics study of phase separation in binary fluid mixtures in periodic and confined domains.

    PubMed

    Gidituri, Harinadha; Anand, D Vijay; Vedantam, Srikanth; Panchagnula, Mahesh V

    2017-08-21

    We investigate the phase separation behavior of binary mixtures in two-dimensional periodic and confined domains using dissipative particle dynamics. Two canonical problems of fluid mechanics are considered for the confined domains: square cavity with no-slip walls and lid-driven cavity with one driven wall. The dynamics is studied for both weakly and strongly separating mixtures and different area fractions. The phase separation process is analyzed using the structure factor and the total interface length. The dynamics of phase separation in the square cavity and lid-driven cavity are observed to be significantly slower when compared to the dynamics in the periodic domain. The presence of the no-slip walls and the inertial effects significantly influences the separation dynamics. Finally, we show that the growth exponent for the strongly separating case is invariant to changes in the inter-species repulsion parameter.

  5. Effect of Relative Material Stiffness of Binary Mixture Components to Compression

    NASA Astrophysics Data System (ADS)

    Bentham, Craig; Dutt, Meenakshi; Hancock, Bruno; Elliott, James

    2006-03-01

    Typical powder blends will have constituent particles which will differ in material properties, such as stiffness, resulting in variation of coordination number and contact slipping state, at a local particle scale. At a macroscopic scale, the relative properties of the various components will influence the force and stress response of the blend to an external load or strain. Of particular curiosity is the distribution of load as a function of contact stiffness. We present numerical results from our studies on binary mixtures with components whose relative stiffness (Young's modulus) has been varied systematically. These mixtures settle under gravity followed by compression at a constant strain rate. In addition, we discuss the correlations between the contact slipping state, stiffness, and the load sustained.

  6. Novel spectrophotometric determination of flumethasone pivalate and clioquinol in their binary mixture and pharmaceutical formulation.

    PubMed

    Abdel-Aleem, Eglal A; Hegazy, Maha A; Sayed, Nour W; Abdelkawy, M; Abdelfatah, Rehab M

    2015-02-05

    This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 μg/mL for FP, and 2-25 μg/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

  7. Dissipative particle dynamics study of phase separation in binary fluid mixtures in periodic and confined domains

    NASA Astrophysics Data System (ADS)

    Gidituri, Harinadha; Anand, D. Vijay; Vedantam, Srikanth; Panchagnula, Mahesh V.

    2017-08-01

    We investigate the phase separation behavior of binary mixtures in two-dimensional periodic and confined domains using dissipative particle dynamics. Two canonical problems of fluid mechanics are considered for the confined domains: square cavity with no-slip walls and lid-driven cavity with one driven wall. The dynamics is studied for both weakly and strongly separating mixtures and different area fractions. The phase separation process is analyzed using the structure factor and the total interface length. The dynamics of phase separation in the square cavity and lid-driven cavity are observed to be significantly slower when compared to the dynamics in the periodic domain. The presence of the no-slip walls and the inertial effects significantly influences the separation dynamics. Finally, we show that the growth exponent for the strongly separating case is invariant to changes in the inter-species repulsion parameter.

  8. Gradient Theory of Binary Nucleation in Carbon Dioxide-Decane Mixtures

    NASA Astrophysics Data System (ADS)

    Obeidat, A.; Li, J.-S.; Wilemski, G.

    2001-03-01

    We use gradient theory to study the binary nucleation of decane and carbon dioxide in high pressure fluid mixtures. The Peng-Robinson equation of state is used to model the thermodynamic properties of the fluid mixtures. This system is intended to be a simple analogue for hydrocarbon particle formation in supercritical carbon dioxide. Density profiles of the mixed droplets are calculated using finite difference techniques with the aid of the Newton-Raphson method. The density profiles are then used to compute the surface tension and free energy of formation of the critical droplets. The results are compared to those of classical nucleation theory. The main advantage of gradient theory compared to classical theory is that the former permits the composition and curvature dependence of the interfacial tension to be introduced in a microscopically sound fashion.

  9. Segregation in conical spouted beds with binary and ternary mixtures of equidensity spherical particles

    SciTech Connect

    San Jose, M.J.; Olazar, M.; Penas, F.J.; Bilbao, J. . Dept. de Ingenieria Quimica)

    1994-07-01

    Spouted beds of conical geometry have been used successfully for treatment of solids with a wide particle size distribution, as happens in coal gasification and in catalytic polymerizations. The versatility of conical spouted beds for stable treatment of binary and ternary mixtures of glass spheres has been proven. The segregation is much lower than that corresponding to other contact methods. It is noteworthy that the larger particles tend to describe trajectories in the upper part of the bed and that the maximum segregation corresponds to mixture with the same proportion of different size particles. A quantitative treatment has been given to the segregation, which is similar to that proposed in the literature for fluidized beds, and consequently, correlations have been obtained for calculation of the mixing index as a function of the contactor geometric factors of bed composition, and of air velocity.

  10. Heat and mass transfer prediction of binary refrigerant mixtures condensing in a horizontal microfin tube

    SciTech Connect

    Koyama, Shigeru; Yu, Jian; Ishibashi, Akira

    1999-07-01

    In the face of the phase-out of HCFC22 for its effect on globe environment, the alternative refrigerant has been paid attention in the refrigeration and heat pump industry. In the present stage, it is found that any pure refrigerant is not a good substitute of HCFC22 for the system in use. The authors have to use binary or ternary refrigerant mixtures as the substitute to meet industrial requirement. But until now, although the heat transfer characteristics of the refrigerant mixtures can be measured in experiments and predicted in some degree, the mass transfer characteristics in condensation process, which is a main part in most systems, can not be clarified by both experimental and theoretical methods. In the present study a non-equilibrium model for condensation of binary refrigerant mixtures inside a horizontal microfin tube is proposed. In this model it is assumed that the phase equilibrium is only established at the vapor-liquid interface, while the bulk vapor and the bulk liquid are in non-equilibrium in the same cross section. The mass transfer characteristic in vapor core is obtained from the analogy between mass and momentum transfer. In the liquid layer, the mass fraction distribution is neglected, but the mass transfer coefficient is treated as infinite that can keep a finite value for the mass transfer rate in liquid phase. From the calculation results compared with the experimental ones for the condensation of HFC134a/HCFC123 and HCFC22/CFC114 mixtures, it is found that the calculated heat flux distribution along the tube axis is in good agreement with that of experiment, and the calculated values of condensing length agree well with the experimental ones. Using the present model, the local mass faction distribution, the diffusion mass transfer rate and the mass transfer characteristics in both vapor and liquid phase are demonstrated. From these results, the effect of mass transfer resistance on condensation heat transfer characteristics for binary

  11. 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

  12. 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

  13. 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

  14. Stationary and transient Soret separation in a binary mixture with a consolute critical point.

    PubMed

    Ryzhkov, Ilya I; Kozlova, Sofia V

    2016-12-01

    The stationary and transient Soret separation in a binary mixture with a consolute critical point is studied theoretically. The mixture is placed between two parallel plates kept at different temperatures. A polymer blend is used as a model system. Analytical solutions are constructed to describe the stationary separation in a binary mixture with variable Soret coefficient. The latter strongly depends on temperature and concentration and enhances near a consolute critical point due to reduced diffusion. As a result, a large concentration gradient is observed locally, while much smaller concentration variations are found in the rest of the layer. It is shown that complete separation can be obtained by applying a small temperature difference first, waiting for the establishment of stationary state, and then increasing this difference again. In this case, the critical temperature lies between hot and cold wall temperatures, while the mixture still remains in the one-phase region. When the initial (mean) temperature or concentration are shifted away from the near-critical values, the separation decreases. The analysis of transient behavior shows that the Soret separation occurs much faster than diffusion to the homogeneous state when the initial concentration is close to the critical one. It happens due to the decrease (increase) of the local relaxation time during the Soret (Diffusion) steps. The transient times of these steps become comparable for small temperature differences or off-critical initial concentrations. An unusual (non-exponential) separation dynamics is observed when the separation starts in the off-critical domain, and then enhances greatly when the system enters into the near-critical region. It is also found that the transient time decreases with increasing the applied temperature difference.

  15. Simulation of Nonisothermal Multiphase Flows of Binary Mixtures in a Porous Media

    NASA Astrophysics Data System (ADS)

    Afanasyev, A. A.

    2010-12-01

    Hydrodynamic simulation of processes in a geothermal system is complicated due to a wide ranges of pressure and temperature in the flows. In deep regions of a system pressure and temperature can be above critical point of water while near the surface normal conditions take place. The transition from a supercritical fluid to a subcritical water and vapor in the flows strongly complicates hydrodynamic simulations. In the case when a geothermal system is saturated with a binary mixture the simulation is much more complex because instead of a single critical point there exist critical lines in a space of thermodynamic parameters of the mixture. Moreover in general case the mixture can split not only in two phases of liquid and gaseous types but also in two dense phases of liquid type and even in three phases. A new approach is proposed for effective simulation of hydrodynamic processes in sub- and supercritical conditions. As opposed to classical thermodynamic phase equilibrium of the mixture is determined via pressure, enthalpy and composition. These variables help to avoid mathematical singularities at critical conditions and allow to determine three phase states. In classical methods a cubic equation of state is used to calculate properties of a mixture for hydrodynamic simulations. In the proposed approach this equation is used prior to hydrodynamic to calculate thermodynamic potential of the mixture in pressure, enthalpy and composition variables. This allows to perform once all complex calculations of the properties prior to hydrodynamic simulations and results in sufficient acceleration of calculations. The potential is used in a problem of conditional extremum for mixture multiphase equilibrium determination in hydrodynamic simulations. This problem of conditional extremum closes transport equations. The approach is applied to simulations of high-temperature water-carbon dioxide mixture flows in a porous media. The mixture phase diagram is analyzed and zones of

  16. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures.

    PubMed

    Almandoz, M C; Sancho, M I; Blanco, S E

    2014-01-24

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π(*)). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture.

  17. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures

    NASA Astrophysics Data System (ADS)

    Almandoz, M. C.; Sancho, M. I.; Blanco, S. E.

    2014-01-01

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π*). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture.

  18. Stokes shift dynamics in (non-dipolar ionic liquid + dipolar solvent) binary mixtures: a semi-molecular theory.

    PubMed

    Pal, Tamisra; Biswas, Ranjit

    2014-10-28

    A semi-molecular theory for studying composition dependent Stokes shift dynamics of a dipolar solute in binary mixtures of (non-dipolar ionic liquid + common dipolar solvent) is developed here. The theory provides microscopic expressions for solvation response functions in terms of static and dynamic structure factors of the mixture components and solute-solvent static correlations. In addition, the theory provides a framework for examining the interrelationship between the time dependent solvation response in and frequency dependent dielectric relaxation of a binary mixture containing electrolyte. Subsequently, the theory has been applied to predict ionic liquid (IL) mole fraction dependent dynamic Stokes shift magnitude and solvation energy relaxation for a dipolar solute, C153, in binary mixtures of an ionic liquid, trihexyltetradecylphosphonium chloride ([P(14,666)][Cl]) with a common dipolar solvent, methanol (MeOH). In the absence of suitable experimental data, necessary input parameters have been obtained from approximate methods. Dynamic shifts calculated for these mixtures exhibit a linear increase with IL mole fraction for the most part of the mixture composition, stressing the importance of solute-IL dipole-ion interaction. Average solvation rates, on the other hand, show a nonlinear IL mole fraction dependence which is qualitatively similar to what has been observed for such binary mixtures with imidazolium (dipolar) ILs. These predictions should be re-examined in suitable experiments.

  19. Study of preferential solvation of 2,6-diaminoanthraquinone in binary mixtures by absorption and fluorescence studies

    NASA Astrophysics Data System (ADS)

    Sasirekha, V.; Ramakrishnan, V.

    2008-08-01

    The role of solute-solvent and solvent-solvent interaction on the preferential solvation characteristics of 2,6-diaminoanthraquinone (DAAQ) has been analysed by monitoring the optical absorption and fluorescence emission spectra. Binary mixtures consist of dimethylformamide (DMF)-ethanol (EtOH), DMF-dimelthylsulfoxide (DMSO), benzene (BZ)-DMF and acetonitrile (ACN)-DMF. The optical absorption spectra maximum and emission spectra maximum of DAAQ show the changes with varying the solvents and change in the composition in the case of binary mixtures. Non-ideal solvation characteristics are observed in all binary mixtures. It is found that at certain concentrations two mixed solvents interact to form a common structure with a ν12 (wave number in cm -1) value not always intermediate ( ν1 and ν2) between the values of the solvents mixed. Synergistic effect is observed in the case of DMF-EtOH mixtures. The preferential solvation parameters local mole fraction X2L, solvation index δS2, exchange constant K12 are calculated in all binary mixtures expect in the case of DMF-BZ mixture and DMF-EtOH mixture in the ground state. We have also monitored excitation wavelength effect on the probe molecule in aprotic polar and protic polar solvents.

  20. 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.

  1. Application of the U and gamma' models in binary sweet taste mixtures.

    PubMed

    Laffort, P; Walsh, R M; Spillane, W J

    2002-07-01

    The U and Gamma' models of sensory interactions, successfully applied in olfaction for several years, are tested here using data from published studies on sweetness. The models are subsequently tested on new data obtained in studies of binary mixtures of four sodium sulfamates. The U model allows for the estimation of a global interaction, whereas the Gamma' model allows for the distinction between that which is due to an intrinsic interaction in the mixture itself and that which may be due to the power function exponents in the mixture. The models give satisfactory predictions for observed phenomena of sweet taste suppression, synergism or pure additivity. Additionally, they appear to be more suitable than other models recently applied in taste, particularly the equiratio model. Application of the models to the sulfamate mixtures, reveals additivity for sodium cyclohexylsulfamate (cyclamate)/potassium cyclohexylsulfamate and sodium cyclohexylsulfamate/sodium exo-2-norbornylsulfamate, respectively; whereas for sodium cyclohexylsulfamate/sodium 3-bromophenylsulfamate, the models revealed a slight hypo addition which is simply due to the dissimilarity values of the power function exponents of the components.

  2. Enhanced gel formation in binary mixtures of nanocolloids with tunable short-range attraction

    NASA Astrophysics Data System (ADS)

    Leheny, R.; Guo, H.; Bertrand, M.; Shendruk, T.; Ramakrishnan, S.; Harden, J.

    We report a combined experimental, theoretical, and simulation study of the phase behavior and microstructural dynamics of concentrated binary mixtures of spherical nanocolloids with a size ratio near two and with a tunable, intrinsic short-range attraction. In the absence of the attraction, the suspensions behave as well mixed, hard-sphere liquids. For sufficiently strong attraction, the suspensions undergo a gel transition. Rheometry measurements show that the fluid-gel boundary of the mixtures does not follow an ideal mixing law, but rather the gel state is stable at weaker interparticle attraction in the mixtures than in the corresponding monodisperse suspensions. X-ray photon correlation spectroscopy measurements reveal that, in contrast with depletion-driven gelation at larger size ratio, gel formation in the mixtures coincides with dynamic arrest of the smaller colloids while the larger colloids remain mobile. Molecular dynamics simulations indicate the arrest results from microphase separation that is caused by a subtle interplay of entropic and enthalpic effects and that drives the smaller particles to form dense regions.

  3. A multiscale transport model for Lennard-Jones binary mixtures based on interfacial friction

    NASA Astrophysics Data System (ADS)

    Bhadauria, Ravi; Aluru, N. R.

    2016-08-01

    We propose a one-dimensional isothermal hydrodynamic transport model for non-reacting binary mixtures in slit shaped nanochannels. The coupled species momentum equations contain viscous dissipation and interspecies friction term of Maxwell-Stefan form. Species partial viscosity variations in the confinement are modeled using the van der Waals one fluid approximation and the local average density method. Species specific macroscopic friction coefficient based Robin boundary conditions are provided to capture the species wall slip effects. The value of this friction coefficient is computed using a species specific generalized Langevin formulation. Gravity driven flow of methane-hydrogen and methane-argon mixtures confined between graphene slit shaped nanochannels are considered as examples. The proposed model yields good quantitative agreement with the velocity profiles obtained from the non-equilibrium molecular dynamics simulations. The mixtures considered are observed to behave as single species pseudo fluid, with the interfacial friction displaying linear dependence on molar composition of the mixture. The results also indicate that the different species have different slip lengths, which remain unchanged with the channel width.

  4. An experimental study of adsorption interference in binary mixtures flowing through activated carbon

    NASA Technical Reports Server (NTRS)

    Madey, R.; Photinos, P. J.

    1983-01-01

    The isothermal transmission through activated carbon adsorber beds at 25 C of acetaldehyde-propane and acetylene-ethane mixtures in a helium carrier gas was measured. The inlet concentration of each component was in the range between 10 ppm and 500 ppm. The constant inlet volumetric flow rate was controlled at 200 cc (STP)/min in the acetaldehyde-propane experiments and at 50 cc (STP)/min in the acetaldehyde-ethane experiments. Comparison of experimental results with the corresponding single-component experiments under similar conditions reveals interference phenomena between the components of the mixtures as evidenced by changes in both the adsorption capacity and the dispersion number. Propane was found to displace acetaldehyde from the adsorbed state. The outlet concentration profiles of propane in the binary mixtures tend to become more diffuse than the corresponding concentration profiles of the one-component experiments. Similar features were observed with mixtures of acetylene and ethane; however, the displacement of acetylene by ethane is less pronounced.

  5. A multiscale transport model for Lennard-Jones binary mixtures based on interfacial friction.

    PubMed

    Bhadauria, Ravi; Aluru, N R

    2016-08-21

    We propose a one-dimensional isothermal hydrodynamic transport model for non-reacting binary mixtures in slit shaped nanochannels. The coupled species momentum equations contain viscous dissipation and interspecies friction term of Maxwell-Stefan form. Species partial viscosity variations in the confinement are modeled using the van der Waals one fluid approximation and the local average density method. Species specific macroscopic friction coefficient based Robin boundary conditions are provided to capture the species wall slip effects. The value of this friction coefficient is computed using a species specific generalized Langevin formulation. Gravity driven flow of methane-hydrogen and methane-argon mixtures confined between graphene slit shaped nanochannels are considered as examples. The proposed model yields good quantitative agreement with the velocity profiles obtained from the non-equilibrium molecular dynamics simulations. The mixtures considered are observed to behave as single species pseudo fluid, with the interfacial friction displaying linear dependence on molar composition of the mixture. The results also indicate that the different species have different slip lengths, which remain unchanged with the channel width.

  6. Dual-Mode Measurement and Theoretical Analysis of Evaporation Kinetics of Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Song, Hanyu; He, Chi-Ruei; Basdeo, Carl; Li, Ji-Qin; Ye, Dezhuang; Kalonia, Devendra; Li, Si-Yu; Fan, Tai-Hsi

    Theoretical and experimental investigations are presented for the precision measurement of evaporation kinetics of binary mixtures using a quartz crystal resonator. A thin layer of light alcohol mixture including a volatile (methanol) and a much less volatile (1-butanol) components is deployed on top of the resonator. The normal or acoustic mode is to detect the moving liquid-vapor interface due to evaporation with a great spatial precision on the order of microns, and simultaneously the shear mode is used for in-situ detection of point viscosity or concentration of the mixture near the resonator. A one-dimensional theoretical model is developed to describe the underlying mass transfer and interfacial transport phenomena. Along with the modeling results, the transient evaporation kinetics, moving interface, and the stratification of viscosity of the liquid mixture during evaporation are simultaneously measured by the impedance response of the shear and longitudinal waves emitted from the resonator. The system can be used to characterize complicated evaporation kinetics involving multi-component fuels. American Chemical Society Petroleum Research Fund, NSF CMMI-0952646.

  7. A multiscale transport model for binary Lennard Jones mixtures in slit nanopores

    NASA Astrophysics Data System (ADS)

    Bhadauria, Ravi; Aluru, N. R.

    2016-11-01

    We present a quasi-continuum multiscale hydrodynamic transport model for one dimensional isothermal, non-reacting binary mixture confined in slit shaped nanochannels. We focus on species transport equation that includes the viscous dissipation and interspecies diffusion term of the Maxwell-Stefan form. Partial viscosity variation is modeled by van der Waals one fluid approximation and the Local Average Density Method. We use friction boundary conditions where the wall-species friction parameter is computed using a novel species specific Generalized Langevin Equation model. The transport model accuracy is tested by predicting the velocity profiles of Lennard-Jones (LJ) methane-hydrogen and LJ methane-argon mixtures in graphene slit channels of different width. The resultant slip length from the continuum model is found to be invariant of channel width for a fixed mixture molar concentration. The mixtures considered are observed to behave as single species pseudo fluid, with the friction parameter displaying a linear dependence on the molar composition. The proposed model yields atomistic level accuracy with continuum scale efficiency.

  8. Three Boundary Conditions for Computing the Fixed-Point Property in Binary Mixture Data

    PubMed Central

    Couto, Joaquina; Lebreton, Mael

    2016-01-01

    The notion of “mixtures” has become pervasive in behavioral and cognitive sciences, due to the success of dual-process theories of cognition. However, providing support for such dual-process theories is not trivial, as it crucially requires properties in the data that are specific to mixture of cognitive processes. In theory, one such property could be the fixed-point property of binary mixture data, applied–for instance- to response times. In that case, the fixed-point property entails that response time distributions obtained in an experiment in which the mixture proportion is manipulated would have a common density point. In the current article, we discuss the application of the fixed-point property and identify three boundary conditions under which the fixed-point property will not be interpretable. In Boundary condition 1, a finding in support of the fixed-point will be mute because of a lack of difference between conditions. Boundary condition 2 refers to the case in which the extreme conditions are so different that a mixture may display bimodality. In this case, a mixture hypothesis is clearly supported, yet the fixed-point may not be found. In Boundary condition 3 the fixed-point may also not be present, yet a mixture might still exist but is occluded due to additional changes in behavior. Finding the fixed-property provides strong support for a dual-process account, yet the boundary conditions that we identify should be considered before making inferences about underlying psychological processes. PMID:27893868

  9. Discriminative Stimulus Effects of Binary Drug Mixtures: Studies with Cocaine, MDPV, and Caffeine

    PubMed Central

    Abbott, Megan; Galindo, Kayla; Rush, Elise L.; Rice, Kenner C.; France, Charles P.

    2016-01-01

    Illicit drug preparations often include more than one pharmacologically active compound. For example, cocaine and synthetic cathinones [e.g., 3,4-methylenedioxypyrovalerone (MDPV)] are often mixed with caffeine before sale. Caffeine is likely added to these preparations because it is inexpensive and legal; however, caffeine might also mimic or enhance some of the effects of cocaine or MDPV. In these studies, male Sprague-Dawley rats were trained to discriminate 10 mg/kg cocaine from saline, and the discriminative stimulus effects of cocaine, caffeine, and MDPV were evaluated alone and as binary mixtures (cocaine and caffeine, MDPV and caffeine, and cocaine and MDPV) at fixed-dose ratios of 3:1, 1:1, and 1:3 relative to the dose of each drug that produced 50% cocaine-appropriate responding. Dose-addition analyses were used to determine the nature of the drug-drug interactions for each mixture (e.g., additive, supra-additive, or subadditive). Although additive interactions were observed for most mixtures, supra-additive interactions were observed at the 50% effect level for the 1:1 mixture of cocaine and caffeine and at the 80% effect level for all three mixtures of cocaine and caffeine, as well as for the 3:1 and 1:3 mixtures of cocaine and MDPV. These results demonstrate that with respect to cocaine-like discriminative stimulus effects, caffeine can function as a substitute in drug preparations containing either cocaine or MDPV, with enhancements of cocaine-like effects possible under certain conditions. Further research is needed to determine whether similar interactions exist for other abuse-related or toxic effects of drug preparations, including cocaine, synthetic cathinones, and caffeine. PMID:27493274

  10. Discriminative Stimulus Effects of Binary Drug Mixtures: Studies with Cocaine, MDPV, and Caffeine.

    PubMed

    Collins, Gregory T; Abbott, Megan; Galindo, Kayla; Rush, Elise L; Rice, Kenner C; France, Charles P

    2016-10-01

    Illicit drug preparations often include more than one pharmacologically active compound. For example, cocaine and synthetic cathinones [e.g., 3,4-methylenedioxypyrovalerone (MDPV)] are often mixed with caffeine before sale. Caffeine is likely added to these preparations because it is inexpensive and legal; however, caffeine might also mimic or enhance some of the effects of cocaine or MDPV. In these studies, male Sprague-Dawley rats were trained to discriminate 10 mg/kg cocaine from saline, and the discriminative stimulus effects of cocaine, caffeine, and MDPV were evaluated alone and as binary mixtures (cocaine and caffeine, MDPV and caffeine, and cocaine and MDPV) at fixed-dose ratios of 3:1, 1:1, and 1:3 relative to the dose of each drug that produced 50% cocaine-appropriate responding. Dose-addition analyses were used to determine the nature of the drug-drug interactions for each mixture (e.g., additive, supra-additive, or subadditive). Although additive interactions were observed for most mixtures, supra-additive interactions were observed at the 50% effect level for the 1:1 mixture of cocaine and caffeine and at the 80% effect level for all three mixtures of cocaine and caffeine, as well as for the 3:1 and 1:3 mixtures of cocaine and MDPV. These results demonstrate that with respect to cocaine-like discriminative stimulus effects, caffeine can function as a substitute in drug preparations containing either cocaine or MDPV, with enhancements of cocaine-like effects possible under certain conditions. Further research is needed to determine whether similar interactions exist for other abuse-related or toxic effects of drug preparations, including cocaine, synthetic cathinones, and caffeine. U.S. Government work not protected by U.S. copyright.

  11. A law of mixtures for transport properties in binary particulate composites

    SciTech Connect

    Duncan, K.L.; Lodenquai, J.F.; Wagh, A.S.; Goretta, K.C.

    1998-09-01

    A connected-grain model was developed earlier to explain mechanical and thermal properties of porous ceramics and sedimentary rocks. We have now generalized this model for binary particulate composites, based on simulation of a connected-grain structure of individual components of the composites by randomly selecting individual grains and shrinking them. Repetition of this procedure results in a structure of a binary particulate composite that contains channels of individual components, through which transport occurs. We developed a generalized law of mixtures in which transport properties are expressed as scaling relationships that depend on the shrinking parameter expressed as an exponent. This parameter provides the skewness of the distribution of the grains. The model is compared with various transport properties of binary composites reported in the literature. In addition, the model is tested on YBa{sub 2}Cu{sub 3}O{sub x} superconductors and Ag composites that were fabricated in our laboratory and tested for electrical conductivity and elastic modulus. This test demonstrates how the model predicts two entirely different transport properties through their common microstructure and grain-size distribution. {copyright} {ital 1998 American Institute of Physics.}

  12. An alternative classification to mixture modeling for longitudinal counts or binary measures.

    PubMed

    Subtil, Fabien; Boussari, Olayidé; Bastard, Mathieu; Etard, Jean-François; Ecochard, René; Génolini, Christophe

    2017-02-01

    Classifying patients according to longitudinal measures, or trajectory classification, has become frequent in clinical research. The k-means algorithm is increasingly used for this task in case of continuous variables with standard deviations that do not depend on the mean. One feature of count and binary data modeled by Poisson or logistic regression is that the variance depends on the mean; hence, the within-group variability changes from one group to another depending on the mean trajectory level. Mixture modeling could be used here for classification though its main purpose is to model the data. The results obtained may change according to the main objective. This article presents an extension of the k-means algorithm that takes into account the features of count and binary data by using the deviance as distance metric. This approach is justified by its analogy with the classification likelihood. Two applications are presented with binary and count data to show the differences between the classifications obtained with the usual Euclidean distance versus the deviance distance.

  13. Imaging cerebroside-rich domains for phase and shape characterization in binary and ternary mixtures.

    PubMed

    Longo, Marjorie L; Blanchette, Craig D

    2010-07-01

    The objective of this paper is to review phase behavior and shape characterization of cerebroside-rich domains in binary and ternary lipid bilayers, as obtained by microscopy techniques. These lipid mixtures provide a format to examine molecular (e.g. headgroup, tail unsaturation, and tail hydroxylation) and thermodynamic (e.g. temperature and mole percentages) factors that determine phase behavior, molecular partitioning, crystal/atomic scale structure, and microstructure/shape (particularly of phase-separated domains). Microscopy can provide excellent spatial (often with high resolution) characterization of cerebroside-rich domains (and their surroundings) to identify, describe or infer with high certainty these characteristics. In the introduction to this review we review briefly the molecular structure, phase behavior, and intermolecular interactions of cerebrosides, in comparison to ceramides and sphingomyelins and in some binary and biological systems. The bulk of the review is then devoted to microscopy investigations of cerebroside-rich domain microstructure and shape dynamics in binary and ternary (one component is cholesterol) systems. Quantitative and/or high-resolution microscopy techniques have been used to interrogate cerebroside-rich domains such as freeze-fracture electron microscopy, atomic force microscopy, imaging elipsometry, two-photon fluorescence microscopy, and LAURDAN generalized polarization in addition to the laboratory workhorse technique of epifluorescence microscopy that allows a quick often qualitative assessment of microstructure and dynamics. We particularly focus on the information these microscopy investigations have revealed with respect to phase behavior, cholesterol partitioning, domain shape, and determinants of domain shape.

  14. Photophysical Properties of Amino- and Dimethylamino Salicylates in Neat and Binary Solvent Mixtures

    NASA Astrophysics Data System (ADS)

    Aleksiejew, Marek; Józefowicz, Marek; Heldt, Janina R.

    2005-09-01

    The solvation characteristic of 2-methoxy-4-aminobenzoic acid methyl ester (MABAE) and 2- methoxy-4-dimethylaminobenzoic acid methyl ester (MDABAE) in the S0, S1(LE) and S1(ICT) states has been determined by means of solvatochromic shifts in neat and binary solvent mixtures. The multiple linear regression analysis of Kamlet et al. indicates that non-specific dielectric dipoledipole and specific hydrogen-bonding interactions play almost an equal role in defining the position of the absorption and fluorescence maxima. On the basis of the performed analysis of normalized solvatochromic shifts, it has been shown that both solutes are preferentially solvated. For cyclohexane-ethanol (CH-EtOH) binary mixtures the preferential solvation characteristics in the S0, S1(LE) and S1(ICT) states are determined predominantly by the hydrogen-bonding interactions. For both molecules under study the electric dipole moment in the S0, S1(LE) and S1(ICT) states as well as the outer-sphere solvent reorganization energy (λout), intramolecular reorganization energy (λin), and destabilization energy (Edest.) have been determined.

  15. Competitive protein adsorption to soft polymeric layers: binary mixtures and comparison to theory.

    PubMed

    Oberle, Michael; Yigit, Cemil; Angioletti-Uberti, Stefano; Dzubiella, Joachim; Ballauff, Matthias

    2015-02-19

    Nanoparticles immersed in biological fluids readily adsorb proteins. The protein corona thus generated on the surface of the particles largely determines their biological fate. Since biological fluids, e.g., blood plasma, contain a large number of proteins, competitive adsorption must be considered. We study the competitive adsorption of lysozyme, cytochrome c, papain, and RNase A onto a soft charged polymeric layer. The experimental data of binary protein mixtures are compared to a theoretical model taking into account electrostatic and hydrophobic interactions between the proteins and the network. The interactions between bound proteins are modeled within a second virial approximation. The model possesses full generality and can be applied to the adsorption of an arbitrary number of protein types. The parameters describing the adsorption of a single protein type are obtained by isothermal titration calorimetry (ITC), while the competitive adsorption of a binary mixture is studied by fluorescence spectroscopy. The competitive adsorption can be predicted from the data related to the adsorption of the single types without adjustable parameters.

  16. Application of continuous wavelet transformation to the simultaneous kinetic determination of binary mixtures.

    PubMed

    Afkhami, Abbas; Abbasi-Tarighat, Maryam

    2009-04-30

    Wavelet transformation of kinetic profiles as a new and simple method was developed for the simultaneous determination of binary mixtures without prior separation steps. The mathematical explanation of the procedure is illustrated. Daubechies (db), symlet (sym) and discrete meyer wavelet (meyr) from the family of wavelet transforms were selected and applied under the optimal conditions for the resolution of binary mixtures. A model data as well as experimental data were tested. The results from the experimental data relating to the simultaneous spectrophotometric determination of phosphate and silicate based on the formation of phospho- and silico-molybdenum blue complexes in the presence of ascorbic acid, and also simultaneous determination of Co(2+) and Ni(2+) based on their complexation reactions with 1-(2-pyridylazo)-2-naphthol (PAN) in micellar media at pH 6.0 were presented as real models. The proposed method was validated by simultaneous determination of phosphate and silicate in detergent and tap water and also Co(2+) and Ni(2+) in tap water samples.

  17. Quantum cluster equilibrium model of N-methylformamide-water binary mixtures

    NASA Astrophysics Data System (ADS)

    von Domaros, Michael; Jähnigen, Sascha; Friedrich, Joachim; Kirchner, Barbara

    2016-02-01

    The established quantum cluster equilibrium (QCE) approach is refined and applied to N-methylformamide (NMF) and its aqueous solution. The QCE method is split into two iterative cycles: one which converges to the liquid phase solution of the QCE equations and another which yields the gas phase. By comparing Gibbs energies, the thermodynamically stable phase at a given temperature and pressure is then chosen. The new methodology avoids metastable solutions and allows a different treatment of the mean-field interactions within the gas and liquid phases. These changes are of crucial importance for the treatment of binary mixtures. For the first time in a QCE study, the cis-trans-isomerism of a species (NMF) is explicitly considered. Cluster geometries and frequencies are calculated using density functional theory (DFT) and complementary coupled cluster single point energies are used to benchmark the DFT results. Independent of the selected quantum-chemical method, a large set of clusters is required for an accurate thermodynamic description of the binary mixture. The liquid phase of neat NMF is found to be dominated by the cyclic trans-NMF pentamer, which can be interpreted as a linear trimer that is stabilized by explicit solvation of two further NMF molecules. This cluster reflects the known hydrogen bond network preferences of neat NMF.

  18. Quantum cluster equilibrium model of N-methylformamide-water binary mixtures.

    PubMed

    von Domaros, Michael; Jähnigen, Sascha; Friedrich, Joachim; Kirchner, Barbara

    2016-02-14

    The established quantum cluster equilibrium (QCE) approach is refined and applied to N-methylformamide (NMF) and its aqueous solution. The QCE method is split into two iterative cycles: one which converges to the liquid phase solution of the QCE equations and another which yields the gas phase. By comparing Gibbs energies, the thermodynamically stable phase at a given temperature and pressure is then chosen. The new methodology avoids metastable solutions and allows a different treatment of the mean-field interactions within the gas and liquid phases. These changes are of crucial importance for the treatment of binary mixtures. For the first time in a QCE study, the cis-trans-isomerism of a species (NMF) is explicitly considered. Cluster geometries and frequencies are calculated using density functional theory (DFT) and complementary coupled cluster single point energies are used to benchmark the DFT results. Independent of the selected quantum-chemical method, a large set of clusters is required for an accurate thermodynamic description of the binary mixture. The liquid phase of neat NMF is found to be dominated by the cyclic trans-NMF pentamer, which can be interpreted as a linear trimer that is stabilized by explicit solvation of two further NMF molecules. This cluster reflects the known hydrogen bond network preferences of neat NMF.

  19. Quantum cluster equilibrium model of N-methylformamide–water binary mixtures

    SciTech Connect

    Domaros, Michael von; Kirchner, Barbara; Jähnigen, Sascha; Friedrich, Joachim

    2016-02-14

    The established quantum cluster equilibrium (QCE) approach is refined and applied to N-methylformamide (NMF) and its aqueous solution. The QCE method is split into two iterative cycles: one which converges to the liquid phase solution of the QCE equations and another which yields the gas phase. By comparing Gibbs energies, the thermodynamically stable phase at a given temperature and pressure is then chosen. The new methodology avoids metastable solutions and allows a different treatment of the mean-field interactions within the gas and liquid phases. These changes are of crucial importance for the treatment of binary mixtures. For the first time in a QCE study, the cis-trans-isomerism of a species (NMF) is explicitly considered. Cluster geometries and frequencies are calculated using density functional theory (DFT) and complementary coupled cluster single point energies are used to benchmark the DFT results. Independent of the selected quantum-chemical method, a large set of clusters is required for an accurate thermodynamic description of the binary mixture. The liquid phase of neat NMF is found to be dominated by the cyclic trans-NMF pentamer, which can be interpreted as a linear trimer that is stabilized by explicit solvation of two further NMF molecules. This cluster reflects the known hydrogen bond network preferences of neat NMF.

  20. Heat capacity singularity of binary liquid mixtures at the liquid-liquid critical point.

    PubMed

    Méndez-Castro, Pablo; Troncoso, Jacobo; Peleteiro, José; Romaní, Luis

    2013-10-01

    The critical anomaly of the isobaric molar heat capacity for the liquid-liquid phase transition in binary nonionic mixtures is explained through a theory based on the general assumption that their partition function can be exactly mapped into that of the Ising three-dimensional model. Under this approximation, it is found that the heat capacity singularity is directly linked to molar excess enthalpy. In order to check this prediction and complete the available data for such systems, isobaric molar heat capacity and molar excess enthalpy near the liquid-liquid critical point were experimentally determined for a large set of binary liquid mixtures. Agreement between theory and experimental results-both from literature and from present work-is good for most cases. This fact opens a way for explaining and predicting the heat capacity divergence at the liquid-liquid critical point through basically the same microscopic arguments as for molar excess enthalpy, widely used in the frame of solution thermodynamics.

  1. Transport properties of the binary mixtures of the three organic liquids toluene, methanol, and cyclohexane

    NASA Astrophysics Data System (ADS)

    Lapeira, E.; Gebhardt, M.; Triller, T.; Mialdun, A.; Köhler, W.; Shevtsova, V.; Bou-Ali, M. M.

    2017-03-01

    We report on the measurements of diffusion (D), thermodiffusion (DT), and Soret (ST) coefficients in binary pairs of the ternary system toluene-methanol-cyclohexane using different instrumental techniques: microgravity measurements (SODI/DCMIX2) on the International Space Station, thermogravitational column in combination with sliding symmetric tubes, optical beam deflection, optical digital interferometry, and counter flow cell. The binary systems have large regions where the mixtures are either not miscible or the Soret coefficient is negative. All the coefficients have been measured over a wide composition range with the exception of a miscibility gap. Results from different instruments and literature data are in favorable agreement over a broad composition range. Additionally, we have carefully measured the physical properties and the optical contrast factors (∂n/∂c ) p ,T and (∂n/∂T ) p ,c. The latter ones were also calculated using the Looyenga equation. The measurements in methanol-cyclohexane mixture revealed a decay of the diffusion coefficient when approaching the miscibility gap. We have interpreted this in the spirit of the pseudospinodal concept.

  2. PHARMACOKINETIC AND PHARMACODYNAMIC INTERACTION FOR A BINARY MIXTURE OF CHLORPYRIFOS AND DIAZINON IN THE RAT

    SciTech Connect

    Timchalk, Chuck; Poet, Torka S.; Hinman, Melissa N.; Busby, Andrea L.; Kousba, Ahmed A.

    2005-05-15

    Chlorpyrifos (CPF) and diazinon (DZN) are two commonly used organophosphorus (OP) insecticides and potential exists for concurrent exposures. The primary neurotoxic effects from OP pesticide exposures result from the inhibition of acetylcholinesterase (AChE) by their oxon metabolites. The pharmacokinetic and pharmacodynamic impact of acute binary exposures to CPF and DZN in rats were evaluated in this study. Rats were orally administered CPF, DZN or a CPF/DZN mixture (0, 15, 30 or 60 mg/kg) and blood (plasma and RBC), and brain were collected at 0, 3, 6, 12 and 24 h post-dosing, urine was also collected at 24 h. Chlorpyrifos, DZN and their respective metabolites 3,5,6-trichloro-2-pyridinol (TCP) and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP) were quantified in blood and/or urine and cholinesterase (ChE) inhibition was measured in brain, RBCs and plasma. Co-exposure to CPF/DZN at 15/15 mg/kg, did not appreciably alter the pharmacokinetics of CPF, DZN or their metabolites in blood; whereas, a 60/60 mg/kg dose resulted in a transient increase in Cmax, AUC, and decreased clearance of both compounds, likely due to competition between CPF and DZN for CYP450 metabolism. At lower doses, most likely to be encountered in occupational or environmental exposures, the pharmacokinetics were linear. A dose-dependent inhibition of ChE was noted in tissues for both the single and co-exposures. The overall potency for ChE inhibition was greater for CPF than DZN and the binary mixture response appeared to be strongly influenced by CPF. A comparison of the ChE binary response at the low dose (15 mg/kg), where there were no apparent pharmacokinetic interactions, suggested that the overall ChE response was additive. These are the first reported experiments we are aware of that characterize both the pharmacokinetic and pharmacodynamic interactions between CPF and DZN in the rat, and will be used to further develop a binary physiologically based pharmacokinetic and pharmacodynamic

  3. Toxicity of binary mixtures of metals and pyrethroid insecticides to Daphnia magna Straus. Implications for multi-substance risks assessment.

    PubMed

    Barata, Carlos; Baird, D J; Nogueira, A J A; Soares, A M V M; Riva, M C

    2006-06-10

    Two different concepts, termed concentration addition (CA) and independent action (IA), describe general relationships between the effects of single substances and their corresponding mixtures allowing calculation of an expected mixture toxicity on the basis of known toxicities of the mixture components. Both concepts are limited to cases in which all substances in a mixture influence the same experimental endpoint, and are usually tested against a "fixed ratio design" where the mixture ratio is kept constant throughout the studies and the overall concentration of the mixture is systematically varied. With this design, interaction among toxic components across different mixture ratios and endpoints (i.e. lethal versus sublethal) is not assessed. In this study lethal and sublethal (feeding) responses of Daphnia magna individuals to single and binary combinations of similarly and dissimilarly acting chemicals including the metals (cadmium, copper) and the pyrethroid insecticides (lambda-cyhalothrin and deltamethrin) were assayed using a composite experimental design to test for interactions among toxic components across mixture effect levels, mixture ratios, lethal and sublethal toxic effects. To account for inter-experiment response variability, in each binary mixture toxicity assay the toxicity of the individual mixture constituents was also assessed. Model adequacy was then evaluated comparing the slopes and elevations of predicted versus observed mixture toxicity curves with those estimated for the individual components. Model predictive abilities changed across endpoints. The IA concept was able to predict accurately mixture toxicities of dissimilarly acting chemicals for lethal responses, whereas the CA concept did so in three out of four pairings for feeding response, irrespective of the chemical mode of action. Interaction effects across mixture effect levels, evidenced by crossing slopes, were only observed for the binary mixture Cd and Cu for lethal effects

  4. Continuous Wavelet Transform, a powerful alternative to Derivative Spectrophotometry in analysis of binary and ternary mixtures: A comparative study.

    PubMed

    Elzanfaly, Eman S; Hassan, Said A; Salem, Maissa Y; El-Zeany, Badr A

    2015-12-05

    A comparative study was established between two signal processing techniques showing the theoretical algorithm for each method and making a comparison between them to indicate the advantages and limitations. The methods under study are Numerical Differentiation (ND) and Continuous Wavelet Transform (CWT). These methods were studied as spectrophotometric resolution tools for simultaneous analysis of binary and ternary mixtures. To present the comparison, the two methods were applied for the resolution of Bisoprolol (BIS) and Hydrochlorothiazide (HCT) in their binary mixture and for the analysis of Amlodipine (AML), Aliskiren (ALI) and Hydrochlorothiazide (HCT) as an example for ternary mixtures. By comparing the results in laboratory prepared mixtures, it was proven that CWT technique is more efficient and advantageous in analysis of mixtures with severe overlapped spectra than ND. The CWT was applied for quantitative determination of the drugs in their pharmaceutical formulations and validated according to the ICH guidelines where accuracy, precision, repeatability and robustness were found to be within the acceptable limit.

  5. Ethanol, acetic acid, and water adsorption from binary and ternary liquid mixtures on high-silica zeolites.

    PubMed

    Bowen, Travis C; Vane, Leland M

    2006-04-11

    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 high-silica beta zeolite were also compared. The amounts adsorbed were measured using a recently developed technique that accurately measures the changes in adsorbent/liquid mixture density and liquid concentration. This technique allows the adsorption of each compound in a liquid mixture to be measured. Adsorption data for binary mixtures were fit with the dual-site extended Langmuir model, and the parameters were used to predict ternary adsorption isotherms for each compound with reasonable accuracy. In ternary mixtures, acetic acid competed with ethanol and water for adsorption sites and reduced ethanol adsorption more than it reduced water adsorption.

  6. Density and Viscosity of Binary Mixtures of Thiocyanate Ionic Liquids + Water as a Function of Temperature.

    PubMed

    Domańska, U; Królikowska, M

    2012-09-01

    Densities and viscosities have been determined for binary mixtures of the ionic liquids (ILs) 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN], or 1-butyl-4-methylpyridinium thiocyanate [BMPy][SCN], or 1-butyl-1-methylpyrrolidinium thiocyanate [BMPYR][SCN], or 1-butyl-1-methylpiperidinium thiocyanate [BMPIP][SCN] with water over wide range of temperatures (298.15-348.15) K and ambient pressure. The thermal properties of [BMPy][SCN], i.e. glass transition temperature and the heat capacity at glass transition, have been measured using a differential scanning microcalorimetry, DSC. The decomposition of [BMPy][SCN] was detected. The density and viscosity correlations for these systems have been made using an empirical second-order polynomial and by the Vogel-Fulcher-Tammann equation, respectively. The concentration dependences have been described by polynomials. The excess molar volumes and deviations in viscosity have been calculated from the experimental values and were correlated by Redlich-Kister polynomial expansions. The variations of these parameters, with compositions of the mixtures and temperature, have been discussed in terms of molecular interactions. A qualitative analysis of the trend of properties with composition and temperature was performed. Further, the excess partial molar volumes, [Formula: see text] and [Formula: see text], were calculated and discussed. The isobaric expansivities (coefficient of thermal expansion), α, and the excess isobaric expansivities, α(E), were determined for four ILs and their mixtures with water. The results indicate that the interactions of thiocyanate ILs with water is not as strong as with alcohols, which is shown by the positive/slightly negative excess molar volumes in these binary systems. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10953-012-9875-7) contains supplementary material, which is available to authorized users.

  7. Solubilization of pentanol by cationic surfactants and binary mixtures of cationic surfactants

    SciTech Connect

    Morgan, M.E.

    1993-12-31

    The research reported here has included studies of the solubilization of pentanol in hexadecylpyridinium chloride (CPC), trimethyletetradecylammonium chloride (C{sub 14}Cl), benzyldimethyltetradecylammonium chloride (C{sub 14}BzCl), benzyldimethylhexadecylpyridinium chloride (C{sub 16}BzCl), hexadecyltrimethylammonium bromide (CTAB), and binary mixtures of CPC + C{sub 16}BzCl and C{sub 14}Cl + C{sub 14}BzCl. Rather than using calorimetric methods, this project will employ headspace chromatography to measure solubilization of pentanol over a wide range of solute concentrations. While not yielding as much thermodynamic data as calorimetry, headspace chromatography is a more direct measure of the extent of solubilization. Using headspace chromatography, is a more direct measure of the extent of solubilization. Using headspace chromatography, this study will seek to determine whether strongly synergistic mixture ratios exist in the case of binary cationic surfactant systems. There are two equilibria in the pentanol-water-surfactant system: (1) The pentanol solubilized in micelles is in equilibrium with the monomeric pentanol in solution, and (2) the monomeric pentanol is in equilibrium with the pentanol in the vapor above the solution. To establish the link between the two equilibria, a sample of the vapor above pure liquid pentanol must be collected, in order to find the activity of pentanol in solution. Also, a calibration curve for various concentrations of pentanol in solution. From this type of data it is possible to infer both the concentration of pentanol solubilized in micelles and the concentrations of pentanol in the ``bulk`` solution outside the micelles. The method is equally applicable to systems containing a single surfactant as well as mixtures of surfactants.

  8. Size segregation in dense, dry, inclined flows of binary granular mixtures

    NASA Astrophysics Data System (ADS)

    Larcher, Michele; Jenkins, James T.

    2013-04-01

    Despite the importance of particle segregation in dense, collisional particle flows, the theoretical framework for its description is still incomplete. Phenomenological theories exist, such as those described by Gray and Ancey [1] that produce plausible predictions of species' concentrations and mixture velocity for appropriate choices of parameters. However, our goal here is to make such predictions in the context of a more fundamental theory that is based on the inter-particle interactions and that incorporates a measure of the energy of the particle velocity fluctuations. We phrase and solve a problem of particle segregation in a dry flow of two sizes of spheres down an inclined, rigid, bumpy bed in the absence of sidewalls. The flow is assumed to be steady and fully-developed, collisions between particles are dissipative, and the sizes and masses of the particles are not too different. For the mixture, we employ the kinetic theory for identical, inelastic spheres developed by Garzo & Dufty [2], modifying their expression for energy dissipation to take in to account the formation of particle clusters [3]. We incorporate friction in the particle interactions through the introduction of an effective coefficient restitution in the translational energy equation [4]; this accounts for energy lost to the fluctuations in translation velocity due both to their conversion to rotational velocity fluctuations and their dissipation due to sliding friction. We employ a theory for segregation in a binary mixture of spheres by Arnarson and Jenkins [5] that is appropriate for particles with relatively small differences in size and mass. We compare the predictions of species' concentration, mixture concentration and mixture velocity to the results of numerical simulations carried out by Tripathi and Khakhar [6]. We employ the particle sizes, masses and interaction parameters of their simulation in the theory; however, because the measures of size and mass difference employed in

  9. Structural properties of methanol-water binary mixtures within the quantum cluster equilibrium model.

    PubMed

    Matisz, G; Kelterer, A-M; Fabian, W M F; Kunsági-Máté, S

    2015-04-07

    Density functional theory (B3LYP-D3, M06-2X) has been used to calculate the structures, interaction energies and vibrational frequencies of a set of 93 methanol-water clusters of different type (cubic, ring, spiro, lasso, bicyclic), size and composition. These interaction energies have been used within the framework of the Quantum Cluster Equilibrium Theory (QCE) to calculate cluster populations as well as thermodynamic properties of binary methanol-water mixtures spanning the whole range from pure water to pure methanol. The necessary parameters amf and bxv of the QCE model were obtained by fitting to experimental isobars of MeOH-H2O mixtures with different MeOH content. The cubic and spiro motifs dominate the distribution of methanol-water clusters in the mixtures with a maximum of mixed clusters at x(MeOH) = 0.365. Reasonable agreement with experimental data as well as earlier molecular dynamics simulations was found for excess enthalpies H(E), entropies S(E) as well as Gibbs free energies of mixing G(E). In contrast, heat capacities Cp and C showed only poor agreement with experimental data.

  10. Microscopic structure and dynamics of glass like domains in a low density binary mixture

    NASA Astrophysics Data System (ADS)

    Varughese, Anna; Jose, Prasanth P.

    2016-10-01

    We present results from extensive equilibrium molecular dynamic simulations of a binary Lennard Jones 80:20 mixture. Our study focuses on the changes in structural and dynamic properties of this system during its transition from a stable phase to an unstable phase as temperature reduces. This system, phase separate into a mixture of glass like domains and gas at lowest temperatures. We compute coarse-grained density(CGD) to identify density distribution in the system, which shows formation of very dense domains. Studies of bond order parameter shows a mixture of crystal structures in these domains at low temperatures. These results show that the structure of the dense domains formed at low density is akin to glassy domains that is found in studies of glass transition at high density, at low temperatures. Our studies on mean square displacement of particles at various state points shows pronounced sub-diffusive regime and plateau that marks the existence of dynamic arrest due to cage formation known in the studies of glassy and supercooled liquids.

  11. Tracking three-phase coexistences in binary mixtures of hard plates and spheres

    NASA Astrophysics Data System (ADS)

    Aliabadi, Roohollah; Moradi, Mahmood; Varga, Szabolcs

    2016-02-01

    The stability of demixing phase transition in binary mixtures of hard plates (with thickness L and diameter D) and hard spheres (with diameter σ) is studied by means of Parsons-Lee theory. The isotropic-isotropic demixing, which is found in mixtures of large spheres and small plates, is very likely to be pre-empted by crystallization. In contrast, the nematic-nematic demixing, which is obtained in mixtures of large plates and small spheres, can be stabilized at low diameter ratios (σ/D) and aspect ratios (L/D). At intermediate values of σ/D, where the sizes of the components are similar, neither the isotropic-isotropic nor the nematic-nematic demixing can be stabilized, but a very strong fractionation takes place between a plate rich nematic and a sphere rich isotropic phases. Our results show that the excluded volume interactions are capable alone to explain the experimental observation of the nematic-nematic demixing, but they fail in the description of isotropic-isotropic one [M. Chen et al., Soft Matter 11, 5775 (2015)].

  12. Theoretical Analysis of Heat Pump Cycle Characteristics with Pure Refrigerants and Binary Refrigerant Mixtures

    NASA Astrophysics Data System (ADS)

    Kagawa, Noboru; Uematsu, Masahiko; Watanabe, Koichi

    In recent years there has been an increasing interest of the use of nonazeotropic binary mixtures to improve performance in heat pump systems, and to restrict the consumption of chlorofluorocarbon (CFC) refrigerants as internationally agreed-upon in the Montreal Protocol. However, the available knowledge on the thermophysical properties of mixtures is very much limited particularly with respect to quantitative information. In order to examine cycle performance for Refrigerant 12 (CCl2F2) + Refrigerant 22 (CHClF2) and Refrigerant 22 + Refrigerant 114 (CClF2-CClF2) systems which are technically important halogenated refrigerant mixtures, the heat pump cycle analysis in case of using pure Refrigerants 12, 22 and 114 was theoretically carried out in the present paper. For the purpose of systematizing the heat pump cycle characteristics with pure refrigerants, the cycle analysis for Refrigerants 502, 13B1, 152a, 717 (NH3) and 290 (C3H8) was also examined. It became clear that the maximum coefficients of performance with various refrigerants were obtained at the reduced condensing temperature being 0.9 when the same temperature difference between condensing and evaporating temperature was chosen.

  13. Distinguishing between donors and their relatives in complex DNA mixtures with binary models.

    PubMed

    Slooten, K

    2016-03-01

    While likelihood ratio calculations were until the recent past limited to the evaluation of mixtures in which all alleles of all donors are present in the DNA mixture profile, more recent methods are able to deal with allelic dropout and drop-in. This opens up the possibility to obtain likelihood ratios for mixtures where this was not previously possible, but it also means that a full match between the alleged contributor and the crime stain is no longer necessary. We investigate in this article what the consequences are for relatives of the actual donors, because they typically share more alleles with the true donor than an unrelated individual. We do this with a semi-continuous binary approach, where the likelihood ratios are based on the observed alleles and the dropout probabilities for each donor, but not on the peak heights themselves. These models are widespread in the forensic community. Since in many cases a simple model is used where a uniform dropout probability is assumed for all (or for all unknown) contributors, we explore the extent to which this alters the false positive probabilities for relatives of donors, compared to what would have been obtained with the correct probabilities of dropout for each donor.

  14. Shear viscosity for a heated granular binary mixture at low density.

    PubMed

    Montanero, José María; Garzó, Vicente

    2003-02-01

    The shear viscosity for a heated granular binary mixture of smooth hard spheres at low density is analyzed. The mixture is heated by the action of an external driving force (Gaussian thermostat) that exactly compensates for cooling effects associated with the dissipation of collisions. The study is made from the Boltzmann kinetic theory, which is solved by using two complementary approaches. First, a normal solution of the Boltzmann equation via the Chapman-Enskog method is obtained up to first order in the spatial gradients. The mass, heat, and momentum fluxes are determined and the corresponding transport coefficients identified. As in the free cooling case [V. Garzó and J. W. Dufty, Phys. Fluids 14, 1476 (2002)], practical evaluation requires a Sonine polynomial approximation, and here it is mainly illustrated in the case of the shear viscosity. Second, to check the accuracy of the Chapman-Enskog results, the Boltzmann equation is numerically solved by means of the direct simulation Monte Carlo method. The simulation is performed for a system under uniform shear flow, using the Gaussian thermostat to control inelastic cooling. The comparison shows an excellent agreement between theory and simulation over a wide range of values of the restitution coefficients and the parameters of the mixture (masses, concentrations, and sizes).

  15. Saturated nucleate boiling to binary and ternary mixtures on horizontal cylinder

    SciTech Connect

    Peyghambarzadeh, S.M.; Alavi Fazel, S.A.; Azizi, S.; Jamialahmadi, M.

    2009-07-15

    In this investigation, a large number of experiments have been performed to determine saturated nucleate pool boiling heat transfer coefficients of MEA/water and DEA/water binary mixtures and that of water/MEA/DEA ternary mixtures. These heat transfer coefficients have been measured at atmospheric pressure and over a wide range of heat fluxes and solution concentrations. The heat flux has been varied in 14 different levels from 7 to about 230 kW/m{sup 2} and amines concentration has been changed in 10 different levels from zero to 84 wt%. Results show that strong reduction of heat transfer coefficient occurs as a result of mass transfer interference in this phenomenon. Furthermore, in this study, all the correlations proposed during the last years for the prediction of nucleate boiling heat transfer coefficient of mixtures have been categorized in three groups. Some experimental results have been compared with the most accurate representatives of these three groups and the corresponding RMS errors have been calculated. Also, impacts of important existing parameters in these correlations like ideal heat transfer coefficient (h{sub id.}) on the prediction have been discussed. (author)

  16. The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids.

    PubMed

    Costa, Mariana C; Sardo, Mariana; Rolemberg, Marlus P; Coutinho, João A P; Meirelles, Antonio J A; Ribeiro-Claro, Paulo; Krähenbühl, M A

    2009-08-01

    For the first time, the solid-liquid phase diagrams of five binary mixtures of saturated fatty acids are here presented. These mixtures are formed of caprylic acid (C(8:0))+capric acid (C(10:0)), capric acid (C(10:0))+lauric acid (C(12:0)), lauric acid (C(12:0))+myristic acid (C(14:0)), myristic acid (C(14:0))+palmitic acid (C(16:0)) and palmitic acid (C(16:0))+stearic acid (C(18:0)). The information used in these phase diagrams was obtained by differential scanning calorimetry (DSC), X-ray diffraction (XRD), FT-Raman spectrometry and polarized light microscopy, aiming at a complete understanding of the phase diagrams of the fatty acid mixtures. All of the phase diagrams reported here presented the same global behavior and it was shown that this was far more complex than previously imagined. They presented not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules, with implications in various industrial applications.

  17. Thermodynamic scaling of the shear viscosity of Mie n-6 fluids and their binary mixtures.

    PubMed

    Delage-Santacreu, Stephanie; Galliero, Guillaume; Hoang, Hai; Bazile, Jean-Patrick; Boned, Christian; Fernandez, Josefa

    2015-05-07

    In this work, we have evaluated the applicability of the so-called thermodynamic scaling and the isomorph frame to describe the shear viscosity of Mie n-6 fluids of varying repulsive exponents (n = 8, 12, 18, 24, and 36). Furthermore, the effectiveness of the thermodynamic scaling to deal with binary mixtures of Mie n-6 fluids has been explored as well. To generate the viscosity database of these fluids, extensive non-equilibrium molecular dynamics simulations have been performed for various thermodynamic conditions. Then, a systematic approach has been used to determine the gamma exponent value (γ) characteristic of the thermodynamic scaling approach for each system. In addition, the applicability of the isomorph theory with a density dependent gamma has been confirmed in pure fluids. In both pure fluids and mixtures, it has been found that the thermodynamic scaling with a constant gamma is sufficient to correlate the viscosity data on a large range of thermodynamic conditions covering liquid and supercritical states as long as the density is not too high. Interestingly, it has been obtained that, in pure fluids, the value of γ is directly proportional to the repulsive exponent of the Mie potential. Finally, it has been found that the value of γ in mixtures can be deduced from those of the pure component using a simple logarithmic mixing rule.

  18. Selective Adsorption and Selective Transport Diffusion of CO2-CH4 Binary Mixture in Coal Ultramicropores.

    PubMed

    Zhao, Yongliang; Feng, Yanhui; Zhang, Xinxin

    2016-09-06

    The adsorption and diffusion of the CO2-CH4 mixture in coal and the underlying mechanisms significantly affect the design and operation of any CO2-enhanced coal-bed methane recovery (CO2-ECBM) project. In this study, bituminous coal was fabricated based on the Wiser molecular model and its ultramicroporous parameters were evaluated; molecular simulations were established through Grand Canonical Monte Carlo (GCMC) and Molecular Dynamic (MD) methods to study the effects of temperature, pressure, and species bulk mole fraction on the adsorption isotherms, adsorption selectivity, three distinct diffusion coefficients, and diffusivity selectivity of the binary mixture in the coal ultramicropores. It turns out that the absolute adsorption amount of each species in the mixture decreases as temperature increases, but increases as its own bulk mole fraction increases. The self-, corrected, and transport diffusion coefficients of pure CO2 and pure CH4 all increase as temperature or/and their own bulk mole fractions increase. Compared to CH4, the adsorption and diffusion of CO2 are preferential in the coal ultramicropores. Adsorption selectivity and diffusivity selectivity were simultaneously employed to reveal that the optimal injection depth for CO2-ECBM is 800-1000 m at 308-323 K temperature and 8.0-10.0 MPa.

  19. The use of zeta potential as a tool to study phase transitions in binary phosphatidylcholines mixtures.

    PubMed

    Sierra, M B; Pedroni, V I; Buffo, F E; Disalvo, E A; Morini, M A

    2016-06-01

    Temperature dependence of the zeta potential (ZP) is proposed as a tool to analyze the thermotropic behavior of unilamellar liposomes prepared from binary mixtures of phosphatidylcholines in the absence or presence of ions in aqueous suspensions. Since the lipid phase transition influences the surface potential of the liposome reflecting a sharp change in the ZP during the transition, it is proposed as a screening method for transition temperatures in complex systems, given its high sensitivity and small amount of sample required, that is, 70% less than that required in the use of conventional calorimeters. The sensitivity is also reflected in the pre-transition detection in the presence of ions. Plots of phase boundaries for these mixed-lipid vesicles were constructed by plotting the delimiting temperatures of both main phase transition and pre-transition vs. the lipid composition of the vesicle. Differential scanning calorimetry (DSC) studies, although subject to uncertainties in interpretation due to broad bands in lipid mixtures, allowed the validation of the temperature dependence of the ZP method for determining the phase transition and pre-transition temperatures. The system chosen was dipalmitoylphosphatidylcholine/dimyristoyl phosphatidylcholine (DMPC/DPPC), the most common combination in biological membranes. This work may be considered as a starting point for further research into more complex lipid mixtures with functional biological importance.

  20. 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.

  1. 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.

  2. Tracking three-phase coexistences in binary mixtures of hard plates and spheres.

    PubMed

    Aliabadi, Roohollah; Moradi, Mahmood; Varga, Szabolcs

    2016-02-21

    The stability of demixing phase transition in binary mixtures of hard plates (with thickness L and diameter D) and hard spheres (with diameter σ) is studied by means of Parsons-Lee theory. The isotropic-isotropic demixing, which is found in mixtures of large spheres and small plates, is very likely to be pre-empted by crystallization. In contrast, the nematic-nematic demixing, which is obtained in mixtures of large plates and small spheres, can be stabilized at low diameter ratios (σ/D) and aspect ratios (L/D). At intermediate values of σ/D, where the sizes of the components are similar, neither the isotropic-isotropic nor the nematic-nematic demixing can be stabilized, but a very strong fractionation takes place between a plate rich nematic and a sphere rich isotropic phases. Our results show that the excluded volume interactions are capable alone to explain the experimental observation of the nematic-nematic demixing, but they fail in the description of isotropic-isotropic one [M. Chen et al., Soft Matter 11, 5775 (2015)].

  3. Thermodynamic scaling of the shear viscosity of Mie n-6 fluids and their binary mixtures

    SciTech Connect

    Delage-Santacreu, Stephanie; Galliero, Guillaume Hoang, Hai; Bazile, Jean-Patrick; Boned, Christian; Fernandez, Josefa

    2015-05-07

    In this work, we have evaluated the applicability of the so-called thermodynamic scaling and the isomorph frame to describe the shear viscosity of Mie n-6 fluids of varying repulsive exponents (n = 8, 12, 18, 24, and 36). Furthermore, the effectiveness of the thermodynamic scaling to deal with binary mixtures of Mie n-6 fluids has been explored as well. To generate the viscosity database of these fluids, extensive non-equilibrium molecular dynamics simulations have been performed for various thermodynamic conditions. Then, a systematic approach has been used to determine the gamma exponent value (γ) characteristic of the thermodynamic scaling approach for each system. In addition, the applicability of the isomorph theory with a density dependent gamma has been confirmed in pure fluids. In both pure fluids and mixtures, it has been found that the thermodynamic scaling with a constant gamma is sufficient to correlate the viscosity data on a large range of thermodynamic conditions covering liquid and supercritical states as long as the density is not too high. Interestingly, it has been obtained that, in pure fluids, the value of γ is directly proportional to the repulsive exponent of the Mie potential. Finally, it has been found that the value of γ in mixtures can be deduced from those of the pure component using a simple logarithmic mixing rule.

  4. Prediction and assessment of ecogenotoxicity of antineoplastic drugs in binary mixtures.

    PubMed

    Kundi, Michael; Parrella, Alfredo; Lavorgna, Margherita; Criscuolo, Emma; Russo, Chiara; Isidori, Marina

    2016-08-01

    The combined genotoxic effects of four anticancer drugs (5-fluorouracil [5-FU], cisplatin [CDDP], etoposide [ET], and imatinib mesylate [IM]) were studied testing their binary mixtures in two crustaceans that are part of the freshwater food chain, namely Daphnia magna and Ceriodaphnia dubia. Genotoxicity was assessed using the in vivo comet assay. Assessment was based on two distinct effect sizes determined from dose-response experiments. Doses for single and combined exposures expected to result in these effect sizes were computed based on Bliss independence as reference model. Statistical comparison by analysis of variance of single and combined toxicities allowed accepting or rejecting the independency hypothesis. The results obtained for D. magna showed independent action for all mixtures except for IM+5-FU that showed an antagonistic interaction. In C. dubia, most mixtures had antagonist interactions except IM+5-FU and IM+CDDP that showed Bliss independence. Despite the antagonistic interactions, our results demonstrated that combinations of anticancer drugs could be of environmental concern because effects occur at very low concentrations that are in the range of concentrations encountered in aquatic systems.

  5. Performance evaluation of a vapor compression heat pump cycle using binary zeotropic refrigerant mixtures

    SciTech Connect

    Koyama, Shigeru; Yara, Tomoyasu

    1999-07-01

    The HCFC refrigerants such as R22 have been used widely as working fluids in refrigeration and air-conditioning systems until now. These refrigerants, however, should be phased out early in the next century to prevent the depletion of the ozone layer. In this situation, binary and/or ternary mixtures composed of HFC and/or natural refrigerants have attracted a great deal of attention due to the following possibilities: (1) to improve the coefficient of performance, COP, by utilizing the temperature glide during phase change processes; (2) to keep the system in more suitable condition for given temperature levels of heat source and heat sink by selecting the combination and composition of refrigerants, etc. From this point of view, in the present study, the performance prediction of a vapor compression heat pump cycle using binary zeotropic refrigerant mixtures is carried out to clarify the effects of the combination of refrigerants, the composition of refrigerants and the size of heat exchangers on COP. In the prediction calculation, a vapor compression heat pump cycle, which consists of a compressor, a vertical plate-fin condenser, an expansion valve, a liquid-vapor separator and a vertical plate-fin evaporator is treated, and the following assumptions are employed: (1) the compression process is isentropic, (2) the expansion process is isenthalpic, (3) the refrigerant is a saturated liquid at the condenser outlet and a superheated vapor at the evaporator outlet, (4) the pressure drop in the condenser is negligible, while that in the evaporator is considered, (5) the local heat transfer characteristics in heat exchangers are considered. The prediction calculation is done for the binary zeotropic refrigerant mixtures of HFC134a/HCFC123 on condition that the heat source water temperature at the condenser outlet, the heat sink water temperature at the evaporator inlet, the water temperature change through condenser and evaporator, the heat load of condenser, the

  6. Simultaneous Detection and Estimation of Catechol, Hydroquinone, and Resorcinol in Binary and Ternary Mixtures Using Electrochemical Techniques

    PubMed Central

    Hossain, Md. Uzzal; Rahman, Md. Toufiqur; Ehsan, Md. Qamrul

    2015-01-01

    Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed with a glassy carbon electrode (GCE) modified with polyglutamic acid (PGA) on the three dihydroxybenzene isomers, catechol (CT), hydroquinone (HQ), and resorcinol (RS). At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers. PMID:26770198

  7. Study of thermodynamic and acoustic behaviour of nicotinic acid in binary aqueous mixtures of D-lactose

    NASA Astrophysics Data System (ADS)

    Sharma, Ravi; Thakur, R. C.

    2017-07-01

    In the present study, the thermodynamic properties such as partial molar volumes, partial molar expansibilities, partial molar compressibilities, partial molar heat capacities and isobaric thermal expansion coefficient of different solutions of nicotinic acid in binary aqueous mixtures of D-lactose have been determined at different temperatures (298.15, 303.15, 308.15, 313.15) K. Masson's equation is used to interpret the data in terms of solute-solute and solute-solvent interactions. In the present study it has been found that nicotinic acid behaves as structure maker in aqueous and binary aqueous mixtures of D-lactose.

  8. Theoretical calculation of transport properties of the noble gases He and Ne and their binary mixtures at low density

    SciTech Connect

    Li Xiufeng; Li Xi

    1996-08-01

    Using the Tang-Toennies potential model and a set of expressions given by J. Kestin et al., we calculate the transport properties of the two noble gases He and Ne and of their binary mixtures, based upon the calculation of the interaction potential. Our calculated results for the transport properties are restricted to low densities but cover the full temperature interval extending from 50 K to the onset of ionization; the mole fraction of the binary mixtures is x{sub 1}:x{sub 2} = 0.25:0.75. Our results are comparable to the best theoretical results given by J. Kestin et al.

  9. Excess Volumes and Excess Isentropic Compressibilities of Binary Liquid Mixtures of Trichloroethylene with Esters at 303.15 K

    NASA Astrophysics Data System (ADS)

    Ramanaiah, S.; Rao, C. Narasimha; Nagaraja, P.; Venkateswarlu, P.

    2015-11-01

    Exces volumes, VE, and excess isentropic compressibilities, κSE, have been reported as a function of composition for binary liquid mixtures of trichloroethylene with ethyl acetate, n-propyl acetate, and n-butyl acetate at 303.15 K. Isentropic compressibilities are calculated using measured sound speeds and density data for pure components and for binary mixtures. Excess volumes and excess isentropic compressibilities are found to be negative for the three systems studied over the entire composition range at 303.15 K, whereas these values become more negative with an increase of carbon chain length. The results are discussed in terms of intermolecular interactions between unlike molecules.

  10. Delineating solute-solvent interactions in binary mixtures of ionic liquids in molecular solvents and preferential solvation approach.

    PubMed

    Khupse, Nageshwar D; Kumar, Anil

    2011-02-03

    The effect of solute-solvent and solvent-solvent interactions on the preferential solvation of solvatochromic indicators in binary mixtures of ionic liquids with molecular solvents has been investigated. The binary mixtures of the pyridinium-based ionic liquids 1-butylpyridinium tetrafluoroborate ([BP][BF4]), 1-butyl-3-methylpyridinium tetrafluoroborate ([3-MBP][BF4]), and 1-butyl-4-methylpyridinium tetrafluoroborate ([4-MBP][BF4]) with molecular solvents like water, methanol, and dichloromethane have been selected for this investigation. The effect of addition of ionic liquids to molecular solvents on the polarity parameters E(T)(N), Kamlet-Taft parameters, hydrogen bond donor ability (HBD) (α), hydrogen bond acceptor ability (HBA) (β), and polarizability (π*) was obtained. The polarity parameters of the mixture display nonideality on addition of ionic liquids to water and dichloromethane. On the other hand, strong synergetic effects were seen in the ionic liquid-methanol binary mixtures. The preferential solvation models have been employed to analyze the collected data in order to achieve information on solute-solvent interactions in these binary mixtures.

  11. Thermodiffusion, molecular diffusion and Soret coefficient of binary and ternary mixtures of n-hexane, n-dodecane and toluene.

    PubMed

    Alonso de Mezquia, David; Wang, Zilin; Lapeira, Estela; Klein, Michael; Wiegand, Simone; Mounir Bou-Ali, M

    2014-11-01

    In this study, the thermodiffusion, molecular diffusion, and Soret coefficients of 12 binary mixtures composed of toluene, n-hexane and n-dodecane in the whole range of concentrations at atmospheric pressure and temperatures of 298.15 K and 308.15 K have been determined. The experimental measurements have been carried out using the Thermogravitational Column, the Sliding Symmetric Tubes and the Thermal Diffusion Forced Rayleigh Scattering techniques. The results obtained using the different techniques show a maximum deviation of 9% for the thermodiffusion coefficient, 8% for the molecular diffusion coefficient and 2% for the Soret coefficient. For the first time we report a decrease of the thermodiffusion coefficient with increasing ratio of the thermal expansion coefficient and viscosity for a binary mixture of an organic ring compound with a short n-alkane. This observation is discussed in terms of interactions between the different components. Additionally, the thermogravitational technique has been used to measure the thermodiffusion coefficients of four ternary mixtures consisting of toluene, n-hexane and n-dodecane at 298.15 K. In order to complete the study, the values obtained for the molecular diffusion coefficient in binary mixtures, and the thermodiffusion coefficient of binary and ternary mixtures have been compared with recently derived correlations.

  12. Effects of binary mixtures of inducers (toluene analogs) and of metals on bioluminescence induction of a recombinant bioreporter strain.

    PubMed

    Kong, In Chul

    2014-10-13

    This paper investigated the effects of binary mixtures of bioluminescence inducers (toluene, xylene isomers, m-toluate) and of metals (Cu, Cd, As(III), As(V), and Cr) on bioluminescence activity of recombinant (Pm-lux) strain KG1206. Different responses and sensitivities were observed depending on the types and concentrations of mixtures of inducers or metals. In the case of inducer mixtures, antagonistic and synergistic modes of action were observed, whereas metal mixtures showed all three modes of action. Antagonistic mode of action was most common for mixtures of indirect inducers, which showed bioluminescence ranging from 29% to 62% of theoretically expected effects (P(E)). On the other hand, synergistic mode of action was observed for mixtures of direct and indirect inducers, which showed bioluminescence between 141% and 243% of P(E). In the case of binary metal mixtures, bioluminescence activities were ranged from 62% to 75% and 113% to 164% of P(E) for antagonistic and synergistic modes of action, respectively (p-values 0.0001-0.038). Therefore, mixture effects could not be generalized since they were dependent on both the types and concentrations of chemicals, suggesting that biomonitoring may constitute a better strategy by investigating types and concentrations of mixture pollutants at contaminated sites.

  13. Effects of Binary Mixtures of Inducers (Toluene Analogs) and of Metals on Bioluminescence Induction of a Recombinant Bioreporter Strain

    PubMed Central

    Kong, In Chul

    2014-01-01

    This paper investigated the effects of binary mixtures of bioluminescence inducers (toluene, xylene isomers, m-toluate) and of metals (Cu, Cd, As(III), As(V), and Cr) on bioluminescence activity of recombinant (Pm-lux) strain KG1206. Different responses and sensitivities were observed depending on the types and concentrations of mixtures of inducers or metals. In the case of inducer mixtures, antagonistic and synergistic modes of action were observed, whereas metal mixtures showed all three modes of action. Antagonistic mode of action was most common for mixtures of indirect inducers, which showed bioluminescence ranging from 29% to 62% of theoretically expected effects (P(E)). On the other hand, synergistic mode of action was observed for mixtures of direct and indirect inducers, which showed bioluminescence between 141% and 243% of P(E).In the case of binary metal mixtures, bioluminescence activities were ranged from 62% to 75% and 113% to 164% of P(E) for antagonistic and synergistic modes of action, respectively (p-values 0.0001–0.038). Therefore, mixture effects could not be generalized since they were dependent on both the types and concentrations of chemicals, suggesting that biomonitoring may constitute a better strategy by investigating types and concentrations of mixture pollutants at contaminated sites. PMID:25313497

  14. Separation of fine binary mixtures under vibration in a gas-solid fluidized bed with dense medium.

    PubMed

    Jin, Haibo; Tong, Zemin; Schlaberg, H Inaki; Zhang, Jiyu

    2005-12-01

    The coke-slag mixture discharged from water-air generators not only causes a serious environmental problem, but also is a potential resource. In order to obtain a high economic return, separation of fine binary mixtures in a vibrating fluidized bed with dense media was experimentally investigated. The effects of volume ratio (mono-component volume to dense medium volume or binary mixture volume to dense medium volume), the fluidization velocity and vibration parameters on separation efficiency are discussed. The experimental results show that vibration can prevent the coalescence and growth of bubbles and improve fluidization properties of particles and the stability of bed density. The major factors associated with separating efficiency are discussed. Based on the experiments, the ratio of the volume of particles to bed volume and the vibration conditions are also reported. It was found that the separation efficiency for a fine coke-slag mixture was greater than 70% and close to 80% under optimal conditions.

  15. Combinatorial approach for the rapid determination of thermochromic behavior of binary and ternary cholesteric liquid crystalline mixtures.

    PubMed

    van der Werff, Louise C; Robinson, Andrea J; Kyratzis, Ilias L

    2012-11-12

    A combinatorial approach was developed for the rapid determination of thermochromic behavior of a large number of binary and ternary sterol based thermochromic liquid crystalline formulations. A binary mixture containing cholesteryl oleyl carbonate and cholesteryl nonanoate, and ternary mixtures also containing a third component, either cholesteryl oleate, cholesteryl benzoate, cholesteryl 2,4-dichlorobenzoate or cholesteryl propionate, were formulated via solvent deposition into a black Teflon coated aluminum 96 well plate. The temperature of the well plate was then varied, and the color appearance of the deposited mixture in each well was recorded. This approach allowed expedient examination of the thermochromic behavior for a large range of liquid crystal formulations. The accuracy of the rapid combinatorial technique was validated on selected thermochromic liquid crystal mixture compositions by comparing well thermochromic output with that observed using UV-vis spectroscopy on material produced in gram quantities.

  16. Joint effects of heavy metal binary mixtures on seed germination, root and shoot growth, bacterial bioluminescence, and gene mutation.

    PubMed

    Kong, In Chul

    2013-05-01

    This investigation was to assess the joint effects of metal binary mixtures on seed germination, root and shoot growth, bacterial bioluminescence, and gene mutation based on the one toxic unit (1 TU) approach. Different sensitivities and orders of toxicity of metal mixtures were observed among the bioassays. In general, mostly additive or antagonistic effects were observed, while almost no synergistic effects by the binary metal mixtures in all bioassays. Therefore, the combined effects of heavy metals in the different bioassays were difficult to generalize since they were dependent on both chemical type and the organism used in each bioassay. However, these results indicate that a battery of bioassays with mixture chemicals as opposed to just a single assay with single metal is a better strategy for the bioassessment of environmental pollutants.

  17. Investigation of binary coating material mixtures using grazing incidence EUV-reflectometry

    NASA Astrophysics Data System (ADS)

    Balasa, I.; Neiers, X.; Mende, M.; Jensen, L.; Ristau, D.

    2014-10-01

    Having been of special interest in thin film technology for a long time already, mixtures of coating materials are still in the focus of research aiming for highest performance in high power as well as in ultra-short pulse laser applications. On the one hand, coating material combinations allow customizing the coating for a certain application by modifying advantageously the refractive index or the band gap energy. On the other hand, that technology is essential in the production of Rugate-filters, using gradually varied refractive index profiles. Therefore, it is of special interest to get insight into the composition of such mixed layers, not only in terms of refractive index and absorption coefficient, but also to evaluate the fractions of materials involved for gaining a better understanding, and therefore to reach highest possible reproducibility for production of such kind of thin films. In this work, single layers of binary mixtures of aluminum oxide, aluminum fluoride, and silicon dioxide are studied with respect to their composition using extreme ultraviolet reflectometry (EUV-R). As the penetration depth of EUV radiation is only a few tens of nanometers under grazing incidence, this non-invasive measurement technique is sensitive to the near surface composition of the film. Therefore it allows investigating the layer material independently of the substrate on which it was deposited. Using specific absorption edges of the involved materials in the EUV spectrum, an empirical correlation between EUV response and mixture ratio is developed and compared to the deep ultraviolet (VUV) absorption edges of the mixture materials.

  18. Equilibrium and non-equilibrium concentration fluctuations in a critical binary mixture.

    PubMed

    Giavazzi, Fabio; Fornasieri, Alessandro; Vailati, Alberto; Cerbino, Roberto

    2016-10-01

    When a macroscopic concentration gradient is present across a binary mixture, long-ranged non-equilibrium concentration fluctuations (NCF) appear as a consequence of the coupling between the gradient and spontaneous equilibrium velocity fluctuations. Long-ranged equilibrium concentration fluctuations (ECF) may be also observed when the mixture is close to a critical point. Here we study the interplay between NCF and critical ECF in a near-critical mixture aniline/cyclohexane in the presence of a vertical concentration gradient. To this aim, we exploit a commercial optical microscope and a simple, custom-made, temperature-controlled cell to obtain simultaneous static and dynamic scattering information on the fluctuations. We first characterise the critical ECF at fixed temperature T above the upper critical solution temperature Tc, in the wide temperature range [Formula: see text] (°)C. In this range, we observe the expected critical scaling behaviour for both the scattering intensity and the mass diffusion coefficient and we determine the critical exponents [Formula: see text], [Formula: see text] and [Formula: see text], which are found in agreement with the 3D Ising values. We then study the system in the two-phase region (T < T c). In particular, we characterise the interplay between ECF and NCF when the mixture, initially at a temperature Ti, is rapidly brought to a temperature T f > T i. During the transient, a vertical diffusive mass flux is present that causes the onset of NCF, whose amplitude vanishes with time, as the flux goes to zero. We also study the time dependence of the equilibrium scattering intensity I eq, of the crossover wave vector q co and of the diffusion coefficient D during diffusion and find that all these quantities exhibit an exponential relaxation enslaved to the diffusive kinetics.

  19. Ringlike spin segregation of binary mixtures in a high-velocity rotating drum

    NASA Astrophysics Data System (ADS)

    Decai, Huang; Ming, Lu; Gang, Sun; Yaodong, Feng; Min, Sun; Haiping, Wu; Kaiming, Deng

    2012-03-01

    This study presents molecular dynamics simulations on the segregation of binary mixtures in a high-velocity rotating drum. Depending on the ratio between the particle radius and density, similarities to the Brazil-nut effect and its reverse form are shown in the ringlike spin segregation patterns in radial direction. The smaller and heavier particles accumulated toward the drum wall, whereas the bigger and lighter particles accumulated toward the drum center. The effects of particle radius and density on the segregation states were quantified and the phase diagram of segregation in the ρb/ρs - rb/rs space was plotted. The observed phenomena can be explained by the combined percolation and the buoyancy effects.

  20. SUPPLEMENTARY COMPARISON: SIM.QM-S1: Bilateral comparison of NIST and CENAM binary gas mixtures

    NASA Astrophysics Data System (ADS)

    Guenther, Frank; Perez-Castorena, Alejandro

    2009-01-01

    Ten compressed gas cylinders from NIST containing binary mixtures with propane, carbon monoxide, carbon dioxide or nitric oxide, all of them with nitrogen balance, were shipped to CENAM for the purpose of bilateral comparison between CENAM and NIST. CENAM utilized its own gravimetrically prepared Primary Reference Materials (PRM) to measure the respective concentrations and reported to NIST. The cylinders were shipped back to NIST for verification of their value. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  1. Direct observation in 3d of structural crossover in binary hard sphere mixtures

    NASA Astrophysics Data System (ADS)

    Statt, Antonia; Pinchaipat, Rattachai; Turci, Francesco; Evans, Robert; Royall, C. Patrick

    2016-04-01

    For binary fluid mixtures of spherical particles in which the two species are sufficiently different in size, the dominant wavelength of oscillations of the pair correlation functions is predicted to change from roughly the diameter of the large species to that of the small species along a sharp crossover line in the phase diagram [C. Grodon et al., J. Chem. Phys. 121, 7869 (2004)]. Using particle-resolved colloid experiments in 3d we demonstrate that crossover exists and that its location in the phase diagram is in quantitative agreement with the results of both theory and our Monte-Carlo simulations. In contrast with previous work [J. Baumgartl et al., Phys. Rev. Lett. 98, 198303 (2007)], where a correspondence was drawn between crossover and percolation of both species, in our 3d study we find that structural crossover is unrelated to percolation.

  2. Microwave dielectric relaxation studies of hydrogen bonded polar binary mixtures of isobutanol and aniline

    NASA Astrophysics Data System (ADS)

    Vishwam, T.; Murthy, V. R. K.

    2013-03-01

    The molecular interaction between the polar systems of isobutanol and aniline for various mole fractions at different temperatures were studied by determining the frequency dependent complex dielectric permittivity by using the open-ended coaxial probe technique method in the microwave frequency range from 20 MHz to 20 GHz. The geometries are optimized at HF and B3LYP with 6-31G and 6-31G+ basis sets. Dipole moments of the binary mixtures are calculated from the dielectric data using Higasi's method and compared with the theoretical results. Conformational analysis of the formation of hydrogen bond between the isobutanol and aniline is supported by the FT-IR and molecular polarizability calculations. The average relaxation times are calculated from their respective Cole-Cole plots. The activation entropy, activation enthalpy and Kirkwood correlation 'g' factor, excess permittivities (ɛE), Bruggeman parameters (fB) have also been determined for isobutanol and aniline and the results were correlated.

  3. Laminar convection in binary mixture of hydromagnetic flow with radiative heat transfer. I, II

    NASA Astrophysics Data System (ADS)

    Alabraba, M. A.; Bestman, A. R.; Ogulu, A.

    1992-09-01

    The hydromagnetic flow of a thermally radiating binary mixture of an incompressible fluid is studied. Both the Soret and Dufour effects are considered when the fluid is not chemically reacting. When the gas is optically thin the resultant system of ordinary differential equations could be solved in a closed form. Generally, the problem is reduced to a set of integral equations which are tackled by perturbation and iteration. The hydromagnetic flow in a vertical channel with heat and mass transfer is studied when a chemical reaction is present. For the general integral equation for radiative flux and in the absence of the Dufour term, the problem is reduced to a set of coupled integral equations which are solved iteratively. The results are compared with the solutions obtained when a chemical reaction is absent.

  4. Biosorption of binary mixtures of copper and cobalt by Penicillium brevicompactum.

    PubMed

    Tsekova, Kolishka; Ianis, Maria; Dencheva, Vera; Ganeva, Sonya

    2007-01-01

    This work reports on a study of the biosorption of copper and cobalt, both singly and in combination (in equimolar concentrations), by the resting cells of Penicillium brevicompactum. Equilibrium batch sorption studies were carried out at 30 degrees C and pH 5.0 for a contact time of 1 hour to guarantee that equilibrium was reached. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The adsorption of binary mixtures of heavy metal solutions on the fungal biomass was found to be of competitive type where the adsorption capacity for any single metal decreased in the presence of the other. The cobalt ions showed a higher affinity for Penicillium brevicompactum than the copper ions.

  5. Structure formation in binary mixtures of lipids and detergents: self-assembly and vesicle division.

    PubMed

    Noguchi, Hiroshi

    2013-01-14

    Self-assembly dynamics in binary surfactant mixtures and structure changes of lipid vesicles induced by detergent solution are studied using coarse-grained molecular simulations. Disk-shaped micelles, the bicelles, are stabilized by detergents surrounding the rim of a bilayer disk of lipids. The self-assembled bicelles are considerably smaller than bicelles formed from vesicle rupture, and their size is determined by the concentrations of lipids and detergents and the interactions between the two species. The detergent-adsorption induces spontaneous curvature of the vesicle bilayer and results in vesicle division into two vesicles or vesicle rupture into worm-like micelles. The division occurs mainly via the inverse pathway of the modified stalk model. For large spontaneous curvature of the monolayers of the detergents, a pore is often opened, thereby leading to vesicle division or worm-like micelle formation.

  6. Structure formation in binary mixtures of lipids and detergents: Self-assembly and vesicle division

    NASA Astrophysics Data System (ADS)

    Noguchi, Hiroshi

    2013-01-01

    Self-assembly dynamics in binary surfactant mixtures and structure changes of lipid vesicles induced by detergent solution are studied using coarse-grained molecular simulations. Disk-shaped micelles, the bicelles, are stabilized by detergents surrounding the rim of a bilayer disk of lipids. The self-assembled bicelles are considerably smaller than bicelles formed from vesicle rupture, and their size is determined by the concentrations of lipids and detergents and the interactions between the two species. The detergent-adsorption induces spontaneous curvature of the vesicle bilayer and results in vesicle division into two vesicles or vesicle rupture into worm-like micelles. The division occurs mainly via the inverse pathway of the modified stalk model. For large spontaneous curvature of the monolayers of the detergents, a pore is often opened, thereby leading to vesicle division or worm-like micelle formation.

  7. Long-wave morphological instabilities in the directional solidification of a dilute binary mixture

    NASA Technical Reports Server (NTRS)

    Riley, D. S.; Davis, S. H.

    1990-01-01

    Long-wave instabilities in a directionally-solidified binary mixture may occur in several limits. Sivashinsky (1983) identified a small-segregation-coefficient limit and obtained a weakly nonlinear evolution equation governing subcritical two-dimensional bifurcation. Brattkus and Davis (1988) identified a near-absolute-stability limit and obtained a strongly nonlinear evolution equation governing supercritical two-dimensional bifurcation. The present investigation identifies a third strongly nonlinear evolution equation, arising in the small-segregation-coefficient, large-surface-energy limit. This equation links both of the former and describes the change from the sub- to super-critical bifurcations. This study sets the previous long-wave analyses into a logical framework.

  8. Long-wave morphological instabilities in the directional solidification of a dilute binary mixture

    NASA Astrophysics Data System (ADS)

    Riley, D. S.; Davis, S. H.

    1990-04-01

    Long-wave instabilities in a directionally-solidified binary mixture may occur in several limits. Sivashinsky (1983) identified a small-segregation-coefficient limit and obtained a weakly nonlinear evolution equation governing subcritical two-dimensional bifurcation. Brattkus and Davis (1988) identified a near-absolute-stability limit and obtained a strongly nonlinear evolution equation governing supercritical two-dimensional bifurcation. The present investigation identifies a third strongly nonlinear evolution equation, arising in the small-segregation-coefficient, large-surface-energy limit. This equation links both of the former and describes the change from the sub- to super-critical bifurcations. This study sets the previous long-wave analyses into a logical framework.

  9. Beyond mean-field properties of binary dipolar Bose mixtures at low temperatures

    NASA Astrophysics Data System (ADS)

    Pastukhov, Volodymyr

    2017-02-01

    We rigorously analyze the low-temperature properties of homogeneous three-dimensional two-component Bose mixture with dipole-dipole interaction. For such a system the effective hydrodynamic action that governs the behavior of low-energy excitations is derived. The infrared structure of the exact single-particle Green's functions is obtained in terms of macroscopic parameters, namely the inverse compressibility and the superfluid density matrices. Within the one-loop approximation we calculate some of the most relevant observable quantities and give the beyond mean-field stability condition for the binary dipolar Bose gas in the dilute limit. A brief variational derivation of the coupled equations that describe macroscopic hydrodynamics of the system in the external nonuniform potential at zero temperature is presented.

  10. Phase separation of a critical binary mixture subjected to a temperature gradient

    NASA Astrophysics Data System (ADS)

    Assenheimer, Michel; Khaykovich, Boris; Steinberg, Victor

    1994-08-01

    We present experimental results on phase separation of a binary mixture of isobutyric acid and water in a thin horizontal, extended layer at the critical concentration, x c, and in the vicinity of the consolute temperature, T c, subjected to a vertical temperature gradient spanning the critical temperature. For relatively small temperature gradients, spinodal decomposition- like patterns are stabilized. A bubble pattern appears for slightly larger temperature gradients, suprisingly always near the hotter boundary, even when T hot > T c. For still larger temperature gradients, polygon morphologies are observed. Their boundaries are probably formed by some kind of surface tension driven instability caused by the nonuniform surface tension along the bubble's interface. However, hydrodynamic instabilities alone have not been able to explain the novel morphologies. The average area of the cellular patterns varies strongly with T c - T cold and Δ T across the fluid layer, whereas the mean area of the bubble like patterns changes just slightly.

  11. Effect of electric field on reentrance transition in a binary mixture of liquid crystals

    NASA Astrophysics Data System (ADS)

    Kumari, Sunita; Singh, S.

    2015-12-01

    Employing a phenomenological mean field theory, we analyze the effect of an electric field on the N - SmA phase transition for pure liquid crystal and on the reentrant nematic phase in a binary mixture of liquid crystals exhibiting the phase sequence I - N - SmA - NR on cooling. The basic idea of the work is to explain the phase transition behavior of the system by assuming that certain Landau coefficients associated with the order parameters coupling terms of the free-energy density expansion are field dependent. These parameters play a crucial role and show a rapid variation at the SmA - NR transition as compared to the SmA - N transition.

  12. Asymptotic modelling of the flow of a thermal binary gas mixture in a microchannel

    NASA Astrophysics Data System (ADS)

    Gatignol, R.; Croizet, C.

    2014-12-01

    The paper purpose is to investigate asymptotic models to describe the basic physical phenomena of flows of a thermal binary gas mixture in coplanar microchannels. The steady flows of gases are described by the Navier-Stokes-Fourier equations, with first order slip boundary conditions for the velocities and jump boundary conditions for the temperatures on the microchannel walls. Taking into account the small parameter equal to the ratio of the two longitudinal and transversal lengths, an asymptotic model is proposed, corresponding to low Mach numbers and to low or moderate Knudsen numbers. Several aspects of the solutions are discussed. We pay attention to the influence of the temperature gradient which is present along the walls. In particular, it is shown that a change in the temperature gradient can induce a change in the longitudinal flow direction. Finally, a result of DSMC similation and the corresponding asymptotic solution are compared.

  13. Evaluation of ultrasonic scattering in human cancellous bone by using a binary mixture model.

    PubMed

    Guo, Xiasheng; Zhang, Dong; Gong, Xiufen

    2007-01-07

    A weak scattering model based on small perturbations in a binary mixture is developed to estimate the ultrasonic scattering from human cancellous bone, which is modelled as a random isotropic continuum containing identical scatters. Ultrasonic scattering is determined by both velocity fluctuation and density fluctuation, when k(2)a(2) < 1 is satisfied. Two kinds of trabeculae thickness distributions, i.e. even distribution and Gauss distribution, are applied in the calculation of attenuation and backscattering. Frequency dependence of the backscatter coefficient is found to be Af(3.13) and Af(2.84) with the Gauss distribution and an even distribution, respectively. Both backscattering and attenuation change significantly against porosity for the case of high porosity. The predicted results are close to the measured ones from the literature. The errors of this theoretical model are also discussed in this paper.

  14. Simultaneous determination of a binary mixture of pantoprazole sodium and itopride hydrochloride by four spectrophotometric methods.

    PubMed

    Ramadan, Nesrin K; El-Ragehy, Nariman A; Ragab, Mona T; El-Zeany, Badr A

    2015-02-25

    Four simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of a binary mixture containing Pantoprazole Sodium Sesquihydrate (PAN) and Itopride Hydrochloride (ITH). Method (A) is the derivative ratio method ((1)DD), method (B) is the mean centering of ratio spectra method (MCR), method (C) is the ratio difference method (RD) and method (D) is the isoabsorptive point coupled with third derivative method ((3)D). Linear correlation was obtained in range 8-44 μg/mL for PAN by the four proposed methods, 8-40 μg/mL for ITH by methods A, B and C and 10-40 μg/mL for ITH by method D. The suggested methods were validated according to ICH guidelines. The obtained results were statistically compared with those obtained by the official and a reported method for PAN and ITH, respectively, showing no significant difference with respect to accuracy and precision.

  15. Colloidal binary mixtures at fluid-fluid interfaces under steady shear: structural, dynamical and mechanical response†

    PubMed Central

    Zell, Zachary A.; Squires, Todd M.; Isa, Lucio

    2015-01-01

    We experimentally study the link between structure, dynamics and mechanical response of two-dimensional (2D) binary mixtures of colloidal microparticles spread at water/oil interfaces. The particles are driven into steady shear by a microdisk forced to rotate at a controlled angular velocity. The flow causes particles to layer into alternating concentric rings of small and big colloids. The formation of such layers is linked to the local, position-dependent shear rate, which triggers two distinct dynamical regimes: particles either move continuously (“Flowing”) close to the microdisk, or exhibit intermittent “Hopping” between local energy minima farther away. The shear-rate-dependent surface viscosity of the monolayers can be extracted from a local interfacial stress balance, giving “macroscopic” flow curves whose behavior corresponds to the distinct microscopic regimes of particle motion. Hopping Regions reveal a higher resistance to flow compared to the Flowing Regions, where spatial organization into layers reduces dissipation. PMID:26347409

  16. Ecotoxicity of binary mixtures of Microcystis aeruginosa and insecticides to Daphnia pulex.

    PubMed

    Asselman, J; Janssen, C R; Smagghe, G; De Schamphelaere, K A C

    2014-05-01

    In aquatic ecosystems, mixtures of chemical and natural stressors can occur which may significantly complicate risk assessment approaches. Here, we show that effects of binary combinations of four different insecticides and Microcystis aeruginosa, a toxic cyanobacteria, on Daphnia pulex exhibited distinct interaction patterns. Combinations with chlorpyrifos and tetradifon caused non-interactive effects, tebufenpyrad caused an antagonistic interaction and fenoyxcarb yielded patterns that depended on the reference model used (i.e. synergistic with independent action, additive with concentration addition). Our results demonstrate that interactive effects cannot be generalised across different insecticides, not even for those targeting the same biological pathway (i.e. tebufenpyrad and tetradifon both target oxidative phosphorylation). Also, the concentration addition reference model provided conservative predictions of effects in all investigated combinations for risk assessment. These predictions could, in absence of a full mechanistic understanding, provide a meaningful solution for managing water quality in systems impacted by both insecticides and cyanobacterial blooms.

  17. A New Simplified Local Density Model for Adsorption of Pure Gases and Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Hasanzadeh, M.; Dehghani, M. R.; Feyzi, F.; Behzadi, B.

    2010-12-01

    Adsorption modeling is an important tool for process simulation and design. Many theoretical models have been developed to describe adsorption data for pure and multicomponent gases. The simplified local density (SLD) approach is a thermodynamic model that can be used with any equation of state and offers some predictive capability with adjustable parameters for modeling of slit-shaped pores. In previous studies, the SLD model has been utilized with the Lennard-Jones potential function for modeling of fluid-solid interactions. In this article, we have focused on application of the Sutherland potential function in an SLD-Peng-Robinson model. The advantages and disadvantages of using the new potential function for adsorption of methane, ethane, carbon dioxide, nitrogen, and three binary mixtures on two types of activated carbon are illustrated. The results have been compared with previous models. It is shown that the new SLD model can correlate adsorption data for different pressures and temperatures with minimum error.

  18. Self-Propulsion Mechanism of Active Janus Particles in Near-Critical Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Samin, Sela; van Roij, René

    2015-10-01

    Gold-capped Janus particles immersed in a near-critical binary mixture can be propelled using illumination. We employ a nonisothermal diffuse interface approach to investigate the self-propulsion mechanism of a single colloid. We attribute the motion to body forces at the edges of a micronsized droplet that nucleates around the particle. Thus, the often-used concept of a surface velocity cannot account for the self-propulsion. The particle's swimming velocity is related to the droplet shape and size, which is determined by a so-called critical isotherm. Two distinct swimming regimes exist, depending on whether the droplet partially or completely covers the particle. Interestingly, the dependence of the swimming velocity on temperature is nonmonotonic in both regimes.

  19. Generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture

    NASA Astrophysics Data System (ADS)

    Felderhof, B. U.

    2017-08-01

    The method employed by Einstein to derive his famous relation between the diffusion coefficient and the friction coefficient of a Brownian particle is used to derive a generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture. The expression is compared with the one derived by de Groot and Mazur from irreversible thermodynamics and later by Batchelor for a Brownian suspension. A different result was derived by several other workers in irreversible thermodynamics. For a nearly incompressible solution, the generalized Einstein relation agrees with the expression derived by de Groot and Mazur. The two expressions also agree to first order in solute density. For a Brownian suspension, the result derived from the generalized Smoluchowski equation agrees with both expressions.

  20. Generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture.

    PubMed

    Felderhof, B U

    2017-08-21

    The method employed by Einstein to derive his famous relation between the diffusion coefficient and the friction coefficient of a Brownian particle is used to derive a generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture. The expression is compared with the one derived by de Groot and Mazur from irreversible thermodynamics and later by Batchelor for a Brownian suspension. A different result was derived by several other workers in irreversible thermodynamics. For a nearly incompressible solution, the generalized Einstein relation agrees with the expression derived by de Groot and Mazur. The two expressions also agree to first order in solute density. For a Brownian suspension, the result derived from the generalized Smoluchowski equation agrees with both expressions.

  1. Detection of Fe2+ in acetonitrile/water mixture by new 8-hydroxyquinolin based sensor through metal displacement mechanism

    NASA Astrophysics Data System (ADS)

    Karaoglu, Kaan; Turker Akcay, H.; Yilmaz, Ismail

    2017-04-01

    A 8-hydroxyquinoline-based (8-HQ) fluorescent ligand (2) was designed and synthesized by condensation of pyridine-2-carboxaldehide with 2-(quinolin-8-yloxy)acetohydrazide (1). Fluorometric titrations with various metal ions in 1:1 M ratio showed that Cu2+ and Ni2+ ions were fully quenched the fluorescence intensity of 2. But, a significant enhancement in the fluorescent intensity was observed when the bound Ni2+ and Cu2+ ions in the 2–Ni and 2–Cu complexes were displaced by Cr3+ and Fe+2 ions, respectively. While 2–Ni exhibited low sensitivity toward Cr3+ ion, the fluorescent titration measurements showed that 2–Cu could be a good ''on-off-on'' selective and sensitive sensor (S) candidate for determination of Fe2+ in aqueous medium.

  2. Coexistence of two liquid crystalline phases in dihydrosphingomyelin and dioleoylphosphatidylcholine binary mixtures.

    PubMed

    Kinoshita, Masanao; Matsumori, Nobuaki; Murata, Michio

    2014-05-01

    Recently, DHSM, a minor constituent in naturally occurring SMs, was indicated to form a raft-like ordered phase more effectively than a naturally occurring form of SM because DHSM has greater potential to induce the intermolecular hydrogen bond. In order to examine the influence of the DHSM-induced hydrogen bond on the phase segregation, the thermal phase behavior of stearoyl-DHSM/DOPC binary bilayers was examined using calorimetry and fluorescence observation and compared with that of SSM/DOPC binary bilayers. Results revealed that the DHSM/DOPC bilayers undergo phase segregation between two L(α) phases within a limited compositional range. On the other hand, apparent phase separation was not observed above main transition temperature in SSM/DOPC mixtures. Our monolayer measurements showed that the lipid packing of DHSM is less perturbed than that of SSM by the addition of small amount of DOPC, indicating a stronger hydrogen bond between DHSM molecules. Therefore, in DHSM/DOPC binary bilayers, DHSM molecules may locally accumulate to form a DHSM-rich domain due to a DHSM-induced hydrogen bond. On the other hand, excess accumulation of DHSM should be prevented because the difference in the curvature between DHSM and DOPC assemblies causes elastic constraint at the domain boundary between the DHSM-rich and DOPC-rich domains. Competition between the energetic advantages provided by formation of the hydrogen bond and the energetic disadvantage conferred by elastic constraints likely results in L(α)/L(α) phase separation within a limited compositional range.

  3. Effect of estrogenic binary mixtures in the yeast estrogen screen (YES).

    PubMed

    Ramirez, Tzutzuy; Buechse, Andreas; Dammann, Martina; Melching-Kollmuß, Stephanie; Woitkowiak, Claudia; van Ravenzwaay, Bennard

    2014-10-01

    Endocrine disrupting compounds (EDCs) of natural or synthetic origin can interfere with the balance of the hormonal system, either by altering hormone production, secretion, transport, or their binding and consequently lead to an adverse outcome in intact animals. An important aspect is the prediction of effects of combined exposure to two or more EDCs at the same time. The yeast estrogen assay (YES) is a broadly used method to assess estrogenic potential of chemicals. Besides exhibiting good predictivity to identify compounds which interfere with the estrogen receptor, it is easy to handle, rapid and therefore allows screening of a large number of single compounds and varying mixtures. Herein, we applied the YES assay to determine the potential combination effects of binary mixtures of two estrogenic compounds, bisphenol A and genistein, as well as one classical androgen that in vitro also exhibits estrogenic activity, trenbolone. In addition to generating data from combined exposure, we fitted these to a four-parametric logistic dose-response model. As all compounds tested share the same mode of action dose additivity was expected. To assess this, the Loewe model was utilized. Deviations between the Loewe additivity model and the observed responses were always small and global tests based on the whole dose-response data set indicated in general a good fit of the Loewe additivity model. At low concentrations concentration additivity was observed, while at high concentrations, the observed effect was lower than additivity, most likely reflecting receptor saturation. In conclusion, our results suggest that binary combinations of genistein, bisphenol A and trenbolone in the YES assay do not deviate from expected additivity. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Composition dependence of the glass forming ability in binary mixtures: The role of demixing entropy

    NASA Astrophysics Data System (ADS)

    Nandi, Ujjwal Kumar; Banerjee, Atreyee; Chakrabarty, Suman; Bhattacharyya, Sarika Maitra

    2016-07-01

    We present a comparative study of the glass forming ability of binary systems with varying composition, where the systems have similar global crystalline structure (CsCl+fcc). Biased Monte Carlo simulations using umbrella sampling technique show that the free energy cost to create a CsCl nucleus increases as the composition of the smaller particles is decreased. We find that systems with comparatively lower free energy cost to form CsCl nucleus exhibit more pronounced pre-crystalline demixing near the liquid/crystal interface. The structural frustration between the CsCl and fcc crystal demands this demixing. We show that closer to the equimolar mixture, the entropic penalty for demixing is lower and a glass forming system may crystallize when seeded with a nucleus. This entropic penalty as a function of composition shows a non-monotonic behaviour with a maximum at a composition similar to the well known Kob-Anderson (KA) model. Although the KA model shows the maximum entropic penalty and thus maximum frustration against CsCl formation, it also shows a strong tendency towards crystallization into fcc lattice of the larger "A" particles which can be explained from the study of the energetics. Thus for systems closer to the equimolar mixture although it is the requirement of demixing which provides their stability against crystallization, for KA model it is not demixing but slow dynamics and the presence of the "B" particles make it a good glass former. The locally favoured structure around "B" particles is quite similar to the CsCl structure and the incompatibility of CsCl and fcc hinders the fcc structure growth in the KA model. Although the glass forming binary systems studied here are quite similar, differing only in composition, we find that their glass forming ability cannot be attributed to a single phenomenon.

  5. 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.

  6. Composition dependence of the glass forming ability in binary mixtures: The role of demixing entropy.

    PubMed

    Nandi, Ujjwal Kumar; Banerjee, Atreyee; Chakrabarty, Suman; Bhattacharyya, Sarika Maitra

    2016-07-21

    We present a comparative study of the glass forming ability of binary systems with varying composition, where the systems have similar global crystalline structure (CsCl+fcc). Biased Monte Carlo simulations using umbrella sampling technique show that the free energy cost to create a CsCl nucleus increases as the composition of the smaller particles is decreased. We find that systems with comparatively lower free energy cost to form CsCl nucleus exhibit more pronounced pre-crystalline demixing near the liquid/crystal interface. The structural frustration between the CsCl and fcc crystal demands this demixing. We show that closer to the equimolar mixture, the entropic penalty for demixing is lower and a glass forming system may crystallize when seeded with a nucleus. This entropic penalty as a function of composition shows a non-monotonic behaviour with a maximum at a composition similar to the well known Kob-Anderson (KA) model. Although the KA model shows the maximum entropic penalty and thus maximum frustration against CsCl formation, it also shows a strong tendency towards crystallization into fcc lattice of the larger "A" particles which can be explained from the study of the energetics. Thus for systems closer to the equimolar mixture although it is the requirement of demixing which provides their stability against crystallization, for KA model it is not demixing but slow dynamics and the presence of the "B" particles make it a good glass former. The locally favoured structure around "B" particles is quite similar to the CsCl structure and the incompatibility of CsCl and fcc hinders the fcc structure growth in the KA model. Although the glass forming binary systems studied here are quite similar, differing only in composition, we find that their glass forming ability cannot be attributed to a single phenomenon.

  7. Quantifying the rates of relaxation of binary mixtures of amorphous pharmaceuticals with isothermal calorimetry.

    PubMed

    Alem, Naziha; Beezer, Anthony E; Gaisford, Simon

    2010-10-31

    While the use of isothermal calorimetry to quantify the rate of relaxation of one-phase amorphous pharmaceuticals, through application of models, is well documented, the resolution of the models to detect and quantify relaxation in systems containing two independent amorphous phases is not known. Addressing this knowledge gap is the focus of this work. Two fitting models were tested; the Kohlrausch-Williams-Watts model (KWW) and the modified-stretch exponential (MSE). The ability of each model to resolve relaxation processes in binary systems was determined with simulated calorimetric data. It was found that as long as the relaxation time constants of the relaxation processes were with 10(3) of each other, the models could determine that two events were occurring and could quantify the correct reaction parameters of each. With greater differences in the time constants, the faster process always dominates the data and the resolving power of the models is lost. Real calorimetric data were then obtained for two binary amorphous systems (sucrose-lactose and sucrose-indomethacin mixtures). The relaxation behaviour of all the single components was characterised as they relaxed individually to provide reference data. The ability of the KWW model to recover the expected relaxation parameters for two component data was impaired because of their inherently noisy nature. The MSE model reasonably recovered the expected parameters for each component for the sucrose-indomethacin system but not for the sucrose-lactose system, which may indicate a possible interaction in that case.

  8. Highly selective GC stationary phases consisting of binary mixtures of polymeric ionic liquids.

    PubMed

    Zhao, Qichao; Anderson, Jared L

    2010-01-01

    GC stationary phases composed of binary mixtures of two polymeric ionic liquids (PILs), namely, poly(1-vinyl-3-hexylimidazolium) bis[(trifluoromethyl)sulfonyl]imide (poly(ViHIm-NTf(2)))/poly(1-vinyl-3-hexylimidazolium) chloride (poly(ViHIm-Cl)) and poly(1-vinyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl]imide (poly(ViHDIm-NTf(2)))/poly(1-vinyl-3-hexadecylimidazolium) chloride (poly(ViHDIm-Cl)), were evaluated in terms of their on-set bleed temperature and separation selectivity. A total of six neat or binary PIL stationary phases were characterized using the solvation parameter model to investigate the effects of the polymeric cation and anion and PIL composition on the system constants of the resulting stationary phases. The hydrogen bond basicity of the mixed poly(ViHIm-NTf(2))/poly(ViHIm-Cl) stationary phases was enriched linearly with the increase in the poly(ViHIm-Cl) content. Results revealed that tuning the composition of the stationary phase allowed for fine control of the retention factors and separation selectivity for alcohols and carboxylic acids as well as selected ketones, aldehydes, and aromatic compounds. A reversal of elution order was observed for particular classes of analytes when the weight percentage of the chloride-based PIL was increased.

  9. Study the density, ultrasonic and compressibility of binary mixture of aqueous solution of isopropyl alcohol and mustard oil

    NASA Astrophysics Data System (ADS)

    Monupal, Suthar, B.

    2016-05-01

    The ultrasonic velocities, compressibility and bulk modulus of binary mixtures of aqueous solution of isopropyl alcohol with mustard oil have been measured at different concentrations at room temperature. The results are varied with the concentration in such a way i.e. ultrasonic velocity and Bulk Modulus is decreases with the increase in concentration and compressibility is increases with the increase in concentration of aqueous isopropyl alcohol. It is due to molecular interactions present in the mixtures.

  10. Toxicity of individual pharmaceuticals and their mixtures to Aliivibrio fischeri: Evidence of toxicological interactions in binary combinations.

    PubMed

    Di Nica, Valeria; Villa, Sara; Finizio, Antonio

    2017-03-01

    The combined toxicities of binary mixtures of veterinary pharmaceutical active compounds were examined using the bioluminescent bacterium Aliivibrio fischeri as a test organism (Microtox® test). Mixtures were prepared at an equitoxic ratio that corresponded to the inhibitory concentration, 10% (IC10) of individual pharmaceutical active compounds. In addition, the toxicity was determined of a multicomponent mixture that contained all of the investigated pharmaceutical active compounds mixed at a ratio corresponding to their individual predicted no-effect concentration (PNEC) values. The experimental results were successively compared with those obtained by applying the 2 most widely used models for predicting mixture toxicity, the concentration addition (CA) and independent action (IA) models. Although the toxicity of the multicomponent mixture tested was well predicted by the CA and IA models, deviations from the model predictions were found for almost all of the binary mixtures. The deviations from the CA and IA models were greater at lower concentrations, particularly when diclofenac sodium and amoxicillin were present in the mixture. Based on these results, another hypothesis was tested, that of toxicological interactions occurring in binary mixtures (in the direction of synergistic or antagonistic effects), by applying the combination index method, which allowed for computerized quantification of synergism, the additive effect and antagonism. The application of this method confirmed, for at least half of the binary combinations, the clear presence of synergistic deviations at the lowest tested concentrations, with a tendency toward antagonism at the higher ones. In 1 case, a relevant antagonistic interaction was observed. Environ Toxicol Chem 2017;36:815-822. © 2016 SETAC.

  11. Non-equilibrium theory employing enthalpy-based equation of state for binary solid and porous mixtures

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Menon, S. V. G.

    2017-04-01

    A generalized enthalpy-based equation of state, which includes thermal electron excitations and non-equilibrium thermal energies, is formulated for binary solid and porous mixtures. Our approach gives rise to an extra contribution to mixture volume, in addition to those corresponding to average mixture parameters. This excess term involves the difference of thermal enthalpies of the two components, which depend on their individual temperatures. We propose to use the Hugoniot of the components to compute non-equilibrium temperatures in the mixture. These are then compared with the average temperature obtained from the mixture Hugoniot, thereby giving an estimate of non-equilibrium effects. The Birch-Murnaghan model for the zero-temperature isotherm and a linear thermal model are then used for applying the method to several mixtures, including one porous case. Comparison with experimental data on the pressure-volume Hugoniot and shock speed versus particle speed shows good agreement.

  12. IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 1. Binary Solvent Mixtures

    NASA Astrophysics Data System (ADS)

    Acree, William E.

    2013-03-01

    This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in binary organic solvent mixtures. Published solubility data for anthracene, naphthalene, phenanthrene, phenothiazine, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 360 different solute-binary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume.

  13. Investigation of Fickian diffusion in the ternary mixtures of water-ethanol-triethylene glycol and its binary pairs.

    PubMed

    Legros, J C; Gaponenko, Y; Mialdun, A; Triller, T; Hammon, A; Bauer, C; Köhler, W; Shevtsova, V

    2015-11-07

    We present a comprehensive experimental study of isothermal Fickian diffusion in the ternary and binary liquid mixtures of water, ethanol, and triethylene glycol over the entire ternary composition space. 21 ternary mixtures inside the composition triangle have been investigated by means of the Taylor dispersion technique and 30 binary mixtures by Taylor dispersion and/or optical beam deflection in a Soret cell. The scalar binary diffusion coefficient has been determined along all three binary boundaries of the composition space and compared with estimations based on the Stokes-Einstein relation using stick or slip boundary conditions. The four elements of the ternary diffusion matrix and the diffusion eigenvalues were determined over a large portion of the composition triangle. The pseudo-binary diffusion coefficients obtained in Taylor dispersion experiments with either one of the two independent concentrations kept constant are comparable to the two diffusion eigenvalues. One of the two off-diagonal elements of the diffusion matrix is of the same order as the diagonal ones and, hence, not negligible, whereas the other one is approximately one order of magnitude smaller. Where available, our results compare well with literature data. The investigated compositions also comprise the five compositions that are scheduled for microgravity experiments in the ESA DCMIX3 project.

  14. Suppression of turbulent energy cascade due to phase separation in homogenous binary mixture fluid

    NASA Astrophysics Data System (ADS)

    Takagi, Youhei; Okamoto, Sachiya

    2015-11-01

    When a multi-component fluid mixture becomes themophysically unstable state by quenching from well-melting condition, phase separation due to spinodal decomposition occurs, and a self-organized structure is formed. During phase separation, free energy is consumed for the structure formation. In our previous report, the phase separation in homogenous turbulence was numerically simulated and the coarsening process of phase separation was discussed. In this study, we extended our numerical model to a high Schmidt number fluid corresponding to actual polymer solution. The governing equations were continuity, Navier-Stokes, and Chan-Hiliard equations as same as our previous report. The flow filed was an isotropic homogenous turbulence, and the dimensionless parameters in the Chan-Hilliard equation were estimated based on the thermophysical condition of binary mixture. From the numerical results, it was found that turbulent energy cascade was drastically suppressed in the inertial subrange by phase separation for the high Schmidt number flow. By using the identification of turbulent and phase separation structure, we discussed the relation between total energy balance and the structures formation processes. This study is financially supported by the Grand-in-Aid for Young Scientists (B) (No. T26820045) from the Ministry of Education, Cul-ture, Sports, Science and Technology of Japan.

  15. Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

    NASA Astrophysics Data System (ADS)

    Stroev, N. E.; Iosilevskiy, I. L.

    2016-11-01

    Non-congruent gas-liquid phase transition (NCPT) have been studied previously in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a uniformly compressible ideal electronic background /BIM(∼)/. The features of NCPT in improved version of the BIM(∼) model for the same mixture on background of non-ideal electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to equation of state of electronic and ionic subsystems were used in present calculations within the Gibbs-Guggenheim conditions of non-congruent phase equilibrium. Parameters of critical point-line were calculated on the entire range of proportions of mixed ions 0 < X < 1. Strong “distillation” effect was found for NCPT in the present BIM(∼) model. Just similar distillation was obtained in the variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM(∼) in contrast to an explicit existence of the azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications.

  16. High-pressure phase behavior of binary mixtures of octacosane and carbon dioxide

    SciTech Connect

    McHugh, M.A.; Seckner, A.J.; Yogan, T.J.

    1984-11-01

    The high-pressure fluid phase behavior of binary mixtures of octacosane and CO/sub 2/ is experimentally investigated. Solubilities of octacosane in supercritical CO/sub 2/ and mixture molar volumes are determined for isotherms of 34.7, 45.4, 50.2, and 52.0/sup 0/C over a range of pressures from 80 to 325 atm. The solubility data are obtained by two different experimental techniques. The pressure-temperature projection of the two branches of the three-phase solid-liquid-gas freezing point depression curve is also determined. The octacosane-CO/sub 2/ LCEP is determined as 32.2/sup 0/ C and 72.6 atm. The UCEP, which is at a pressure greater than 650 atm, could not be determined due to the pressure limitation of the experimental apparatus. Phase diagram constructions are used qualitatively to explain the observed phase behavior and to provide information on the expected phase behavior of the octacosane-CO/sub 2/ system at pressures higher than those experimentally investigated.

  17. Motions in binary mixtures of hard colloidal spheres: melting of the glass.

    PubMed

    Williams, S R; van Megen, W

    2001-10-01

    Dynamic light-scattering experiments are performed on binary mixtures of hard-sphere-like colloidal suspensions with a size ratio of 0.6. The optical properties of the particles are such that the relative contrast of the two species is very sensitive to temperature, a feature that is exploited to obtain the three partial coherent intermediate scattering functions. The glass transition is identified by the onset of structural arrest, or arrest of the alpha process, on the time scale of the experiment. This is observed in a one-component suspension at a packing fraction of 0.575. The intermediate scattering functions measured on the mixtures quantify how, on introduction of the smaller spheres, the alpha process is released, i.e., how the glass melts. Increasing the fraction of smaller particles causes the alpha process to speed up but, at a given wave vector, also incurs a change to its amplitude in proportion to the change in the (partial) structure factor.

  18. Rescaled density expansions and demixing in hard-sphere binary mixtures.

    PubMed

    López de Haro, M; Tejero, C F

    2004-10-08

    The demixing transition of a binary fluid mixture of additive hard spheres is analyzed for different size asymmetries by starting from the exact low-density expansion of the pressure. Already within the second virial approximation the fluid separates into two phases of different composition with a lower consolute critical point. By successively incorporating the third, fourth, and fifth virial coefficients, the critical consolute point moves to higher values of the pressure and to lower values of the partial number fraction of the large spheres. When the exact low-density expansion of the pressure is rescaled to higher densities as in the Percus-Yevick theory, by adding more exact virial coefficients a different qualitative movement of the critical consolute point in the phase diagram is found. It is argued that the Percus-Yevick factor appearing in many empirical equations of state for the mixture has a deep influence on the location of the critical consolute point, so that the resulting phase diagram for a prescribed equation has to be taken with caution.

  19. Doubled heterogeneous crystal nucleation in sediments of hard sphere binary-mass mixtures.

    PubMed

    Löwen, Hartmut; Allahyarov, Elshad

    2011-10-07

    Crystallization during the sedimentation process of a binary colloidal hard spheres mixture is explored by Brownian dynamics computer simulations. The two species are different in buoyant mass but have the same interaction diameter. Starting from a completely mixed system in a finite container, gravity is suddenly turned on, and the crystallization process in the sample is monitored. If the Peclet numbers of the two species are both not too large, crystalline layers are formed at the bottom of the cell. The composition of lighter particles in the sedimented crystal is non-monotonic in the altitude: it is first increasing, then decreasing, and then increasing again. If one Peclet number is large and the other is small, we observe the occurrence of a doubled heterogeneous crystal nucleation process. First, crystalline layers are formed at the bottom container wall which are separated from an amorphous sediment. At the amorphous-fluid interface, a secondary crystal nucleation of layers is identified. This doubled heterogeneous nucleation can be verified in real-space experiments on colloidal mixtures. © 2011 American Institute of Physics

  20. Multiscale modeling of binary polymer mixtures: Scale bridging in the athermal and thermal regime

    NASA Astrophysics Data System (ADS)

    McCarty, J.; Guenza, M. G.

    2010-09-01

    Obtaining a rigorous and reliable method for linking computer simulations of polymer blends and composites at different length scales of interest is a highly desirable goal in soft matter physics. In this paper a multiscale modeling procedure is presented for the efficient calculation of the static structural properties of binary homopolymer blends. The procedure combines computer simulations of polymer chains on two different length scales, using a united atom representation for the finer structure and a highly coarse-grained approach on the mesoscale, where chains are represented as soft colloidal particles interacting through an effective potential. A method for combining the structural information by inverse mapping is discussed, allowing for the efficient calculation of partial correlation functions, which are compared with results from full united atom simulations. The structure of several polymer mixtures is obtained in an efficient manner for several mixtures in the homogeneous region of the phase diagram. The method is then extended to incorporate thermal fluctuations through an effective χ parameter. Since the approach is analytical, it is fully transferable to numerous systems.

  1. Experimental densities of binary mixtures: Acetic acid with benzene at several temperatures

    NASA Astrophysics Data System (ADS)

    Bolat, Georgiana; Sutiman, Daniel; Lisa, Gabriela

    2011-03-01

    Hydrocarbons are the most commonly used chemicals in the hydrocarbon processing industries. The knowledge of thermodynamic properties of various binary organic or inorganic mixtures is essential in many practical aspects concerning the mass transport and fluid flow. Such properties are important from the fundamental point of view to understand their mixing behaviour (molecular interactions), as well for practical applications (e.g. in the petrochemical industry). The density of acetic acid-benzene mixtures at several temperatures (T = 296.15, 302.15, 308.15, 314.15 and 319.15 K) were measured over the whole composition range and atmospheric pressure, along with the physical-chemical properties of the pure components (e.g. density, viscosity, refractive index at 298.15 K). The excess molar volumes at the above-mentioned temperatures were calculated from experimental data and fitted by using a new polynomial equation comparing the results with the known equation of Redlich-Kister. The excess volumes for acetic acid with benzene were positive and increase with the temperature. Results were analyzed in terms of molecular interactions. This research was financed by the postdoc grant PERFORM-ERA-ID 57649.

  2. Nanophase coexistence and sieving in binary mixtures confined between corrugated walls

    SciTech Connect

    Curry, J.E.; Cushman, J.H.

    1995-08-08

    The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to a corrugated slit micropore which is in thermodynamic equilibrium with its bulk phase counterpart. The micropore has atomically structured walls; one of the which possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions, that inside and that outside the grooves. Transverse solidlike order in the film gives rise to shear stress. Transverse order coupled with packing restrictions give rise to a difference between the pore and bulk fluid mixture compositions. Solidlike order may appear within the grooves only, outside the grooves only, or in both regions simultaneously. As the relative alignment of the walls is shifted the pore fluid undergoes freeze--thaw cycles in one or both regions with associated changes in the shear stress and pore fluid composition. The degree of transverse order in the film is less than would be expected in a pure Lennard-Jones film and fluid-solid phase transitions are gradual as opposed to sudden as seen in pure Lennard-Jones films. The magnitude of the shear stress is greatest when a fluid--solid phase transition occurs in both regions of the pore. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  3. Effects of single pesticides and binary pesticide mixtures on estrone production in H295R cells.

    PubMed

    Prutner, Wiebke; Nicken, Petra; Haunhorst, Eberhard; Hamscher, Gerd; Steinberg, Pablo

    2013-12-01

    The aim of the present study was to determine whether the human adrenocortical carcinoma cell line H295R can be used as an in vitro test system to investigate the effects of binary pesticide combinations on estrone production as biological endpoint. In the first step ten pesticides selected according to a tiered approach were tested individually. The anilinopyrimidines cyprodinil and pyrimethanil as well as the dicarboximides iprodione and procymidone increased estrone concentration, while the triazoles myclobutanil and tebuconazole as well as the strobilurins azoxystrobin and kresoxim-methyl decreased estrone concentration in the supernatant of H295R cells. The N-methylcarbamate methomyl did not show any effects, and the phthalimide captan reduced estrone concentration unspecifically due to its detrimental impact on cellular viability. When cyprodinil and pyrimethanil, which belong to the same chemical group and increase estrone production, were combined, in most of the cases the overall effect was solely determined by the most potent compound in the mixture (i.e., cyprodinil). When cyprodinil and procymidone, which belong to different chemical groups but increase estrone production, were combined, in most cases an additive effect was observed. When cyprodinil, which increased estrone production, was combined with either myclobutanil or azoxystrobin, which decreased estrone production, the overall effect of the mixture was in most cases either entirely determined by myclobutanil or at least partially modulated by azoxystrobin. In conclusion, H295R cells appear to be an adequate in vitro test system to study the effect of combining two pesticides affecting estrone production.

  4. A density-functional theory study of microphase formation in binary Gaussian mixtures

    NASA Astrophysics Data System (ADS)

    Carta, M.; Pini, D.; Parola, A.; Reatto, L.

    2012-07-01

    We use density-functional theory to study the formation of inhomogeneous phases in a binary mixture of particles interacting by repulsive, athermal Gaussian potentials with suitably chosen strengths and ranges. Both the potential parameters and the free-energy functional are the same as those adopted in a previous investigation by other authors (Archer A J, Likos C N and Evans R 2004 J. Phys.: Condens. Matter 16 L297), but here a fully numerical minimization of the functional is performed, without any assumption about the functional form of the density profile. We find lamellar, rod and cluster phases. In the lamellar phase, the two species arrange into intercalating stripes; in the rod and cluster phases, the minority species is localized at the site of a periodic lattice, either triangular (for rods) or body-centred cubic (for clusters), while the other species is distributed non-uniformly in the remaining region, so that it forms a percolating network. The order of the transition from the homogeneous to the inhomogeneous phase and the phase diagram of the mixture are also discussed.

  5. A poromechanical model for coal seams saturated with binary mixtures of CH4 and CO2

    NASA Astrophysics Data System (ADS)

    Nikoosokhan, Saeid; Vandamme, Matthieu; Dangla, Patrick

    2014-11-01

    Underground coal bed reservoirs naturally contain methane which can be produced. In parallel of the production of this methane, carbon dioxide can be injected, either to enhance the production of methane, or to have this carbon dioxide stored over geological periods of time. As a prerequisite to any simulation of an Enhanced Coal Bed Methane recovery process (ECBM), we need state equations to model the behavior of the seam when cleats are saturated with a miscible mixture of CH4 and CO2. This paper presents a poromechanical model of coal seams exposed to such binary mixtures filling both the cleats in the seam and the porosity of the coal matrix. This model is an extension of a previous work which dealt with pure fluid. Special care is dedicated to keep the model consistent thermodynamically. The model is fully calibrated with a mix of experimental data and numerical data from molecular simulations. Predicting variations of porosity or permeability requires only calibration based on swelling data. With the calibrated state equations, we predict numerically how porosity, permeability, and adsorbed amounts of fluid vary in a representative volume element of coal seam in isochoric or oedometric conditions, as a function of the pressure and of the composition of the fluid in the cleats.

  6. The granulation of binary mixtures: the effects of the properties of the component powders on granules.

    PubMed

    Opakunle, W O; Spring, M S

    1976-12-01

    Sulphanilamide and citric acid individually and in various proportions with lactose, have been granulated by massing and screening. There was an optimum blend, that produced granules of maximum mean size and strength, for each binary system examined. The proportion of the components of this optimal blend was dependent on the physical properties of the second component in a mixture with lactose. Results from three systems, lactose:boric acid, lactose:sulphanilamide and lactose:citric acid indicate that although part dissolution of powder during granulation is a factor affecting granule properties, in some systems other physical properties of the second component may become dominant. It is suggested that the combined effect of cohesiveness and wettability of the powders may make the major contribution to granule strength with the sulphanilamide systems. The ultimate mean granule size produced is determined by the wettability or solubiluty of the powders, or both, in all cases examined. The great affinity of citric acid for aqueous binder solution was the dominant factor determining the properties of granules prepared from lactose:citric acid mixtures.

  7. An Exercise on Calibration: DRIFTS Study of Binary Mixtures of Calcite and Dolomite with Partially Overlapping Spectral Features

    ERIC Educational Resources Information Center

    De Lorenzi Pezzolo, Alessandra

    2013-01-01

    Unlike most spectroscopic calibrations that are based on the study of well-separated features ascribable to the different components, this laboratory experience is especially designed to exploit spectral features that are nearly overlapping. The investigated system consists of a binary mixture of two commonly occurring minerals, calcite and…

  8. An Exercise on Calibration: DRIFTS Study of Binary Mixtures of Calcite and Dolomite with Partially Overlapping Spectral Features

    ERIC Educational Resources Information Center

    De Lorenzi Pezzolo, Alessandra

    2013-01-01

    Unlike most spectroscopic calibrations that are based on the study of well-separated features ascribable to the different components, this laboratory experience is especially designed to exploit spectral features that are nearly overlapping. The investigated system consists of a binary mixture of two commonly occurring minerals, calcite and…

  9. 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...

  10. 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...

  11. Herbage nutritive value of tall fescue-bermudagrass binary mixtures fertilized with combinations of nitrogen fertilizer and poultry litter

    USDA-ARS?s Scientific Manuscript database

    Year-round forage production is feasible in much of the southeastern USA through utilization of cool- and warm-season forages. This study determined if productivity and nutritive value in binary mixtures of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] and bermudagrass [Cynodon dactylon (L...

  12. Enhanced toxicity of binary mixtures of larvicidal constituents from Asarum heterotropoides root to Culex pipiens pallens (Diptera: Culicidae).

    PubMed

    Perumalsamy, Haribalan; Kim, Jun-Ran; Kim, Soon-Il; Kwon, Hyung Wook; Ahn, Young-Joon

    2012-01-01

    The toxicity of pellitorine alone or in combination with (-)-asarinin, alpha-asarone, methyleugenol, or pentadecane (1:1, 1:2, 1:3, 2:1, and 3:1 ratios) to third instars from an insecticide-susceptible KS-CP strain and -resistant DJ-CP colony of Culex pipiens pallens Coquillett was evaluated using a direct-contact mortality bioassay. The binary mixture of pellitorine and (-)-asarinin (3:1 ratio) was significantly more toxic against KS-CP larvae (0.95 mg/liter) and DJ-CP larvae (1.07 mg/liter) than either pellitorine (2.08 mg/liter for KS-CP and 2.33 mg/liter for DJ-CP) or (-)-asarinin (11.45 and 12.61 mg/liter) alone. The toxicity of the other binary mixtures (1:1, 1:2, 1:3, and 2:1 ratios) and pellitorine did not differ significantly from each other. Based on the co-toxicity coefficient (CC) and synergistic factor (SF), the three binary mixtures (1:3, 2:1, and 3:1) operated synergistically (CC, 250-390 and SF, 1.4-2.2 for KS-CP; CC, 257-279 and SF, 1.1-2.1 for DJ-CP). The binary mixtures of pellitorine and (-)-asarinin merit further study as potential larvicides for the control of insecticide-resistant mosquito populations.

  13. Dielectric studies of binary mixtures of ethylene glycol mono phenyl ether with 1-butanol at different temperatures

    NASA Astrophysics Data System (ADS)

    Chaube, H. A.; Rana, V. A.

    Static permittivity (ɛ), refractive index (n) and density (ρ) of binary mixtures of ethylene glycol mono phenyl ether (EGMPE) with 1-butanol (1-BuOH) over the entire range of mole fraction and at temperatures (T=303.15, 313.15 and 323.15K) have been measured. From the experimental data, parameters such as excess static permittivity (ɛE), excess permittivity at optical frequency (ɛ∞E), effective Kirkwood correlation factor (geff), corrective Kirkwood correlation factor (gf) and Bruggeman factor (fb) have been calculated to obtain qualitative and quantitative information about the complex formation through H-bond in binary system. In order to predict the static permittivity of polar-polar binary mixtures six mixing rules were applied and for refractive index five mixing rule were applied. Experimental results of permittivity (ɛ) and refractive index (n) are compared with those obtained from theoretical calculations. Excess parameters were fitted to the Redlich-Kister type polynomial equation.

  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. 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

  16. Phase behavior of colloidal dimers and hydrodynamic instabilities in binary mixtures

    NASA Astrophysics Data System (ADS)

    Milinkovic, K.

    2013-05-01

    We use computer simulations to study colloidal suspensions comprised of either bidisperse spherical particles or monodisperse dimer particles. The two main simulation techniques employed are a hybrid between molecular dynamics and stochastic rotation dynamics (MD-SRD), and a Monte Carlo (MC) algorithm. MD-SRD allows us to take Brownian motion and hydrodynamic interactions into account, while we use MC simulations to study equilibrium phase behavior. The first part of this thesis is dedicated to studying the Rayleigh-Taylor-like hydrodynamic instabilities which form in binary colloidal mixtures. Configurations with initially inhomogeneous distributions of colloidal species let to sediment in confinement will undergo the instability, and here we have studied the formation, evolution and the structural organization of the colloids within the instability as a function of the properties of the binary mixture. We found that the distribution of the colloids within the instability does not depend significantly on the composition of the mixtures, but does depend greatly on the relative magnitudes of the particle Peclet numbers. To follow the time evolution of the instability formation we calculated the spatial colloid velocity correlation functions, observing alternating regions in which the particle sedimentation velocities are correlated and anticorrelated. These observations are consistent with the network-like structures which are characteristic for Rayleigh-Taylor instabilities. We also calculated the growth rates of the unstable modes both from our simulation data and theoretically, finding good agreement between the obtained results. The second part of this thesis focuses on the phase behavior of monodisperse dimer systems. We first studied the phase behavior of hard snowman-shaped particles which consist of tangential hard spheres with different diameters. We used Monte Carlo simulations and free energy calculations to obtain the phase diagram as a function of the

  17. Conformational Changes of the Alanine Dipeptide in Water-Ethanol Binary Mixtures.

    PubMed

    Almeida, Glauco G; Cordeiro, João M M; Martín, M Elena; Aguilar, Manuel A

    2016-04-12

    Experimental work developed in the last years has evidenced the capacity of alcohols and polyalcohols to modify the energy landscape of peptides and proteins. However, the mechanism underlying this effect is not clear. Taking as a model system the alanine dipeptide (AD) we perform a QM/MM study in water, ethanol, and a 40-60% in volume water-ethanol mixture. The AD molecule was described at the MP2/aug-cc-pVDZ level. In polar solution, only αR and PPII conformers contribute in an appreciable way to the conformational equilibrium. The final in solution αR-PPII free energy difference is determined from the interplay between the internal energy of the dipeptide and the solute-solvent interaction free energy. Internal energy favors the formation of PPII, whereas, on the contrary, solute-solvent interaction is favorable to αR, so any factor that decreases the solute-solvent interaction free energy will increase the PPII population. The addition of ethanol increases the stability of the PPII conformer. Our results point to the presence of preferential solvation in this system, the composition of the first solvation shell in the binary mixture being dominated by water molecules. Remarkably, this fact does not affect the differential conformational stability that is controlled by long-range interactions. From the analysis of solvent density maps it is concluded that, in the water-ethanol mixture, ethanol molecules are more likely found around the alanine side chain and the carbonyl group, but while in PPII ethanol molecules interact mainly with the carbonyl group of the N-terminal end, in C5 the interaction is with the carbonyl group of the C-terminal end. In αR, ethanol interacts with both carbonyl groups.

  18. Asymmetrical phase separation and gelation in binary mixtures of oppositely charged colloids

    NASA Astrophysics Data System (ADS)

    Zong, Yiwu; Yuan, Guangcui; Han, Charles C.

    2016-07-01

    Two types of colloidal particles, which are nearly the same in chemical composition but carry opposite surface charges, are mixed in water. Depending on the relative proportion of the oppositely charged particles, the process of aggregation leads to the formation of discrete clusters of various sizes in dilute dispersions, and to the development of particle gel networks in more concentrated systems. Due to the significant difference in the absolute values of surface charges (negative particle: -48 mV, positive particle: +24 mV), the phase separation and the gelation behaviors are asymmetric with respect to the mixing ratio. Mixtures with excess negative particles are more stable, while mixtures with excess positive particles are easily affected by phase separation. The hetero-aggregation triggered by the addition of microscopically large macro-ions is similar to what is often observed in a mono-component charged colloidal system, i.e., phase separation occurs through addition of small electrolyte ions. Within the concentration region investigated here, it is clear that the gel line is buried inside the phase separation region. Gelation occurs only when the number and size of the clusters are large and big enough to connect up into a space-spanning network. Our results indicate that, in this binary mixture of oppositely charged colloids, although the interaction between unlike species is attractive and that between like species is repulsive, the onset of gelation is in fact governed by the equilibrium phase separation, as in the case of purely attractive systems with short-range isotropic interaction.

  19. Asymmetrical phase separation and gelation in binary mixtures of oppositely charged colloids.

    PubMed

    Zong, Yiwu; Yuan, Guangcui; Han, Charles C

    2016-07-07

    Two types of colloidal particles, which are nearly the same in chemical composition but carry opposite surface charges, are mixed in water. Depending on the relative proportion of the oppositely charged particles, the process of aggregation leads to the formation of discrete clusters of various sizes in dilute dispersions, and to the development of particle gel networks in more concentrated systems. Due to the significant difference in the absolute values of surface charges (negative particle: -48 mV, positive particle: +24 mV), the phase separation and the gelation behaviors are asymmetric with respect to the mixing ratio. Mixtures with excess negative particles are more stable, while mixtures with excess positive particles are easily affected by phase separation. The hetero-aggregation triggered by the addition of microscopically large macro-ions is similar to what is often observed in a mono-component charged colloidal system, i.e., phase separation occurs through addition of small electrolyte ions. Within the concentration region investigated here, it is clear that the gel line is buried inside the phase separation region. Gelation occurs only when the number and size of the clusters are large and big enough to connect up into a space-spanning network. Our results indicate that, in this binary mixture of oppositely charged colloids, although the interaction between unlike species is attractive and that between like species is repulsive, the onset of gelation is in fact governed by the equilibrium phase separation, as in the case of purely attractive systems with short-range isotropic interaction.

  20. An unconstrained DFT approach to microphase formation and application to binary Gaussian mixtures

    NASA Astrophysics Data System (ADS)

    Pini, Davide; Parola, Alberto; Reatto, Luciano

    2015-07-01

    The formation of microphases in systems of particles interacting by repulsive, bounded potentials is studied by means of density-functional theory (DFT) using a simple, mean-field-like form for the free energy which has already been proven accurate for this class of soft interactions. In an effort not to constrain the configurations available to the system, we do not make any assumption on the functional form of the density profile ρ(r), save for its being periodic. We sample ρ(r) at a large number of points in the unit cell and minimize the free energy with respect to both the values assumed by ρ(r) at these points and the lattice vectors which identify the Bravais lattice. After checking the accuracy of the method by applying it to a one-component generalized exponential model (GEM) fluid with pair potential ɛexp[ - (r/R)4], for which extensive DFT and simulation results are already available, we turn to a binary mixture of Gaussian particles which some time ago was shown to support microphase formation [A. J. Archer, C. N. Likos, and R. Evans, J. Phys.: Condens. Matter 16, L297 (2004)], but has not yet been investigated in detail. The phase diagram which we obtain, that supersedes the tentative one proposed by us in a former study [M. Carta, D. Pini, A. Parola, and L. Reatto, J. Phys.: Condens. Matter 24, 284106 (2012)], displays cluster, tubular, and bicontinuous phases similar to those observed in block copolymers or oil/water/surfactant mixtures. Remarkably, bicontinuous phases occupy a rather large portion of the phase diagram. We also find two non-cubic phases, in both of which one species is preferentially located inside the channels left available by the other, forming helices of alternating chirality. The features of cluster formation in this mixture and in GEM potentials are also compared.

  1. Population inversion of binary Lennard-Jones mixtures in nanoslit pores (a density functional theory study).

    PubMed

    Taghizadeh, Ameneh; Keshavarzi, Ezat Tahmineh

    2011-04-07

    The aim of this work is to investigate the population inversion of binary asymmetric Lennard-Jones mixtures inside nanoslit pores due to confinement effects for both vapor and liquid phases. For this purpose we have used mean field fundamental measure theory, and the effect of different parameters such as interaction strength and size ratios of the components, confinement size, and thermodynamic state on the population distribution of molecules have been studied. It has been shown that in the case of bulk liquid mixtures, increasing the role of confinement effects can lead to preferential adsorption of the component with larger size and weaker intermolecular interactions into the nanopore in spite of its minority in the bulk which is referred as population inversion. This population inversion phenomenon is terminated by a sudden condensation which, interestingly, involves a simultaneous adsorption and desorption for more and less bulk concentrated species, respectively. We have demonstrated that this condensation phenomenon shifts to higher bulk densities with increasing the role of confinement effects such that in some cases population inversion is observable for the whole range of densities. In consideration of the conditions in which vapor Lennard-Jones mixtures undergo capillary condensation, the population distribution of components in the vapor- and liquidlike phases was studied. It has been shown that variation of parameters such as interaction strength and size ratios, temperature, and confinement size can lead to conditions in which capillary condensation is accompanying with a population inversion phenomenon. In these cases, whereas the composition of vaporlike phases is the same as bulk fluid, liquidlike phases are richer in the component with less bulk concentration.

  2. Characterization of dimethylsulfoxide/glycerol mixtures: a binary solvent system for the study of "friction-dependent" chemical reactivity.

    PubMed

    Angulo, Gonzalo; Brucka, Marta; Gerecke, Mario; Grampp, Günter; Jeannerat, Damien; Milkiewicz, Jadwiga; Mitrev, Yavor; Radzewicz, Czesław; Rosspeintner, Arnulf; Vauthey, Eric; Wnuk, Paweł

    2016-07-21

    The properties of binary mixtures of dimethylsulfoxide and glycerol, measured using several techniques, are reported. Special attention is given to those properties contributing or affecting chemical reactions. In this respect the investigated mixture behaves as a relatively simple solvent and it is especially well suited for studies on the influence of viscosity on chemical reactivity. This is due to the relative invariance of the dielectric properties of the mixture. However, special caution must be taken with specific solvation, as the hydrogen-bonding properties of the solvent change with the molar fraction of glycerol.

  3. Adsorption of binary gas mixtures in heterogeneous carbon predicted by density functional theory: on the formation of adsorption azeotropes.

    PubMed

    Ritter, James A; Pan, Huanhua; Balbuena, Perla B

    2010-09-07

    Classical density functional theory (DFT) was used to predict the adsorption of nine different binary gas mixtures in a heterogeneous BPL activated carbon with a known pore size distribution (PSD) and in single, homogeneous, slit-shaped carbon pores of different sizes. By comparing the heterogeneous results with those obtained from the ideal adsorbed solution theory and with those obtained in the homogeneous carbon, it was determined that adsorption nonideality and adsorption azeotropes are caused by the coupled effects of differences in the molecular size of the components in a gas mixture and only slight differences in the pore sizes of a heterogeneous adsorbent. For many binary gas mixtures, selectivity was found to be a strong function of pore size. As the width of a homogeneous pore increases slightly, the selectivity for two different sized adsorbates may change from being greater than unity to less than unity. This change in selectivity can be accompanied by the formation of an adsorption azeotrope when this same binary mixture is adsorbed in a heterogeneous adsorbent with a PSD, like in BPL activated carbon. These results also showed that the selectivity exhibited by a heterogeneous adsorbent can be dominated by a small number of pores that are very selective toward one of the components in the gas mixture, leading to adsorption azeotrope formation in extreme cases.

  4. Molecular dynamics of a binary mixture of twist-bend nematic liquid crystal dimers studied by dielectric spectroscopy.

    PubMed

    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.

  5. Study on volatility and flash point of the pseudo-binary mixtures of sunflowerseed-based biodiesel+ethanol.

    PubMed

    Guo, Yongsheng; Wei, Hui; Yang, Fengjun; Li, Dan; Fang, Wenjun; Lin, Ruisen

    2009-08-15

    Volatility and flash point for the pseudo-binary mixtures of sunflower seed-based biodiesel+ethanol were measured over the entire composition range. The biodiesel was prepared by the transesterification of sunflower seed oil in supercritical methanol without using any catalyst. The vapor pressures of mixtures of biodiesel+ethanol as a function of temperature were measured by comparative ebulliometry with an inclined ebulliometer. The vapor pressures versus composition at different temperatures and temperatures versus composition at different pressures were obtained from Antoine correlations. It is found that ethanol can adjust effectively the volatility and flash point of the biodiesel. The correlation of the flash points with the vapor pressure data for the pseudo-binary mixtures of biodiesel+ethanol displays agreement with the experimental data obtained by closed cup test.

  6. Kinematic viscosities of binary and ternary liquid mixtures involving chloroform, 2-propanol, and 2-butanol at several temperatures

    SciTech Connect

    Sovilj, M.N.

    1995-09-01

    A knowledge of the viscosity of liquids and liquid mixtures is required for the solution of many engineering problems concerning heat transfer, mass transfer, and fluid flow. Experimental kinematic viscosity data are presented for chloroform + 2-propanol + 2-butanol and also for the three constituent binary mixtures at 20, 25, 30, and 35 C. The binary kinematic viscosities have been correlated by the empirical equation obtained by extension of the model of ideal kinematic viscosity of a liquid mixtures. Predicted data agree fairly well with the experimental observations. The ternary kinematic viscosities were fitted by correlations suggested by Al-Besharah et al., Vijayaraghavan et al., and Iulian et al. The best fit was obtained with the relation by Al-Besharah et al.

  7. Ions in a binary asymmetric dipolar mixture: mole fraction dependent Born energy of solvation and partial solvent polarization structure.

    PubMed

    Kashyap, Hemant K; Biswas, Ranjit

    2007-11-14

    Mean spherical approximation (MSA) for electrolyte solution has been extended to investigate the role of partial solvent polarization densities around an ion in a completely asymmetric binary dipolar mixture. The differences in solvent diameters, dipole moments, and ionic size are incorporated systematically within the MSA framework in the present theory for the first time. In addition to the contributions due to difference in dipole moments, the solvent-solvent and ion-solvent size ratios are found to significantly affect the nonideality in binary dipolar mixtures. Subsequently, the theory is used to investigate the role of ion-solvent and solvent-solvent size ratios in determining the nonideality in Born free energy of solvation of a unipositive rigid ion in alcohol-water and dimethyl sulfoxide-acetonitrile mixtures, where the solvent components are represented only by their molecular diameters and dipole moments. Nonideality in Born free energy of solvation in such simplified mixtures is found to be stronger for smaller ions. The slope of the nonideality for smaller alkali metal ions in methanol-water mixture is found to be opposite to that for larger ion, such as quaternary tertiary butyl ammonium ion. For ethanol-water mixtures, the slopes are in the same direction for all the ions studied here. These results are in qualitative agreement with experiments, which is surprising as the present MSA approach does not include the hydrogen bonding and hydrophobic interactions present in the real mixtures. The calculated partial polarization densities around a unipositive ion also show the characteristic deviation from ideality and reveal the microscopic origin of the ion and solvent size dependent preferential solvation. Also, the excess free energy of mixing (in the absence of any ion) for these binary mixtures has been calculated and a good agreement between theory and experiment has been found.

  8. Binary mixtures of waxy wheat and conventional wheat as measured by NIR reflectance.

    PubMed

    Delwiche, Stephen R; Graybosch, Robert A

    2016-01-01

    Waxy wheat contains very low concentration (generally <2%) of amylose in endosperm starch, in contrast to conventional wheat whose starch is typically 20% amylose, with the balance being the branched macromolecule, amylopectin. With the release of a commercial hard winter waxy wheat cultivar in the United States, the grain trade, milling, and processing industries seek to have a rapid technique to ensure the purity of identity preserved waxy wheat lots. Near infrared (NIR) reflectance spectroscopy, a technique widely used in the cereals industry for proximate analysis, is a logical candidate for measuring contamination level and thus is the subject of this study. Two sets of wheat samples, harvested, prepared and scanned one year apart, were used to evaluate the NIR concept. One year consisted of nine pairs of conventional:waxy preparations, with each preparation consisting of 29 binary mixtures ranging in conventional wheat fraction (by weight) of 0-100% (261 spectral samples). The second year was prepared in the same fashion, with 12 preparations, thus producing 348 spectral samples. One year's samples were controlled for protein content and moisture level between pair components in order to avoid the basis for the conventional wheat fraction models being caused by something other than spectral differences attributed to waxy and nonwaxy endosperm. Likewise the second year was controlled by selection of conventional wheat for mixture preparation based on either protein content or cluster analysis of principal components of candidate spectra. Partial least squares regression, one and two-term linear regression, and support vector machine regression models were examined. Validation statistics arising from sets within the same year or across years were remarkably similar, as were those among the three regression types. A single wavelength on second derivative transformed spectra, namely 2290 nm, was effective at estimating the mixture level by weight, with standard

  9. Study of solid surface interactions with binary liquid mixtures and liquid crystals

    NASA Astrophysics Data System (ADS)

    Polak, Robert Dale

    The adsorption profile of a binary liquid mixture against a solid substrate was studied using an optical probe. The effective surface field was controlled by partially coating one half of the glass surface with octadecyltrichlorosilane, while the other half remained bare. On the bare surface, one component of the binary liquid mixture was strongly adsorbed to the surface, and, in the one-phase region, adsorption could be observed far from the bulk transition temperature. This adsorption scales as expected by a normal surface transition in which the surface orders at a higher temperature than the bulk. On the partially coated surface, the adsorption could only be observed very near the bulk critical temperature. Over the course of the first several days of the experiment, the adsorption profile changed, but it eventually became stable. Scaling analysis of the stable surface suggests the possibility that the surface was in the crossover region between normal and ordinary (where the surface and bulk order at the same temperature) surface transitions. In a separate series of experiments, the interaction between a nematic liquid crystal and substrate was studied, in particular, the energetic cost to deviate the surface director from its preferred orientation. To accurately determine the energetic cost, denoted by the polar anchoring coefficient W, of a typical alignment layer/liquid crystal was measured using three techniques. The first is the 'high-electric-field' (HEF) technique was found to give the largest value of W. In the course of the study, the HEF technique was improved by no longer requiring the measurement of capacitance of the sample liquid crystal cell. Also, the source of the large value of W is detected, and a protocol was developed to determine the reliability of the results given by the HEF technique. Two other techniques are used to determine W: the measurement of capacitance in a magnetic field and the measurement of the Frederiks transition at

  10. Five different spectrophotometric methods for determination of Amprolium hydrochloride and Ethopabate binary mixture

    NASA Astrophysics Data System (ADS)

    Hussein, Lobna A.; Magdy, N.; Abbas, Mahmoud M.

    2015-03-01

    Five simple, specific, accurate and precise UV-spectrophotometric methods are adopted for the simultaneous determination of Amprolium hydrochloride (AMP) and Ethopabate (ETH), a binary mixture with overlapping spectra, without preliminary separation. The first method is first derivative of the ratio spectra (1DD) for determination of AMP and ETH at 234.7 nm and 306.8 nm respectively with mean percentage recoveries 99.76 ± 0.907 and 100.29 ± 0.842 respectively. The second method is the mean centering of the ratio spectra for determination of AMP and ETH at 238.8 nm and 313 nm respectively with mean percentage recoveries 100.26 ± 1.018 and 99.94 ± 1.286 respectively. The third method is based on dual wavelength selection for determination of AMP and ETH at 235.3 nm & 308 nm and 244 nm & 268.4 nm respectively with mean percentage recoveries 99.30 ± 1.097 and 100.03 ± 1.065 respectively. The fourth method is ratio difference method for determination of AMP and ETH at 239 nm & 310 nm and 239 nm & 313 nm respectively with mean percentage recoveries 99.27 ± 0.892 and 100.40 ± 1.814 respectively. The fifth one is area under the curve (AUC) method where the areas between 235.6-243 nm and 268.3-275 nm are selected for determination of AMP and ETH with mean percentage recoveries 100.35 ± 1.031 and 100.39 ± 0.956 respectively. These methods are tested by analyzing synthetic mixtures of the two drugs and they are applied to their pharmaceutical veterinary preparation. Methods are validated according to the ICH guidelines and accuracy, precision and repeatability are found to be within the acceptable limit.

  11. Stability of LS and LS2 crystal structures in binary mixtures of hard and charged spheres.

    PubMed

    Hynninen, A-P; Filion, L; Dijkstra, M

    2009-08-14

    We study by computer simulations the stability of various crystal structures in a binary mixture of large and small spheres interacting either with a hard sphere or a screened-Coulomb potential. In the case of hard-core systems, we consider structures that have atomic prototypes CrB, gammaCuTi, alphaIrV, HgBr2, AuTe2, Ag2Se and the Laves phases (MgCu2, MgNi2, and MgZn2) as well as a structure with space group symmetry 74. By utilizing Monte Carlo simulations to calculate Gibbs free energies, we determine composition versus pressure and constant volume phase diagrams for diameter ratios of q=0.74, 0.76, 0.8, 0.82, 0.84, and 0.85 for the small and large spheres. For diameter ratios 0.76 < or = q < or = 0.84, we find the Laves phases to be stable with respect to the other crystal structures that we considered and the fluid mixture. By extrapolating to the thermodynamic limit, we show that the MgZn2 structure is the most stable one of the Laves structures. We also calculate phase diagrams for equally and oppositely charged spheres for size ratio of 0.73 taking into consideration the Laves phases and CsCl. In the case of equally charged spheres, we find a pocket of stable Laves phases, while in the case of oppositely charged spheres, Laves phases are found to be metastable with respect to the CsCl and fluid phases.

  12. A new secondary relaxation in the rigid and planar 1-methylindole: Evidence from binary mixture studies

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Li, Xiangqian; Guo, Yuxing; Wu, Tao; Liu, Ying Dan; Ngai, K. L.; Wang, Li-Min

    2016-12-01

    Found in our recent dielectric study of a planar and rigid glass-former, 1-methylindole (1MID), is an unusual secondary relaxation unrelated in its dynamic properties to the structural α-relaxation. We speculated that it originates from the in-plane motion of the molecules, and the supposedly universal Johari-Goldstein (JG) β-relaxation with strong connection to the structural α-relaxation in rigid glass-formers is not resolved [X. Q. Li et al. J. Chem. Phys. 143, 104505 (2015)]. In this work, dielectric measurements are performed in binary mixtures of 1MID with two aromatics of weak polarity, ethylbenzene (EB) and triphenylethylene (TPE), in the highly viscous regimes near glass transition. EB and TPE have smaller and larger molecular sizes and glass transition temperatures Tg than 1MID, respectively. Strikingly, the results show that the resolved secondary relaxations of 1MID in the two mixtures share the same relaxation time and their temperature dependence as pure 1MID, independent of the mode and degree of dilution. The results indicate that the unusual secondary relaxation is not directly coupled with the α-relaxation, and support the in-plane-rotation interpretation of its origin. On the other hand, the supposedly universal and intermolecular JG β-relaxation coming from the out-of-plane motion of the planar molecule has weaker dielectric strength, and it cannot be resolved from the more intense in-plane-rotation secondary relaxation because the dipole moment of 1MID lies on the plane.

  13. Rayleigh-Bénard convection in binary mixtures with separation ratios near zero

    NASA Astrophysics Data System (ADS)

    Dominguez-Lerma, Marco A.; Ahlers, Guenter; Cannell, David S.

    1995-12-01

    We present an experimental study of convection in binary mixtures with separation ratios Ψ close to zero. Measurements of the Hopf frequency for Ψ<0 were used to determine the relationship between Ψ and the mass concentration x with high precision. These results are consistent with but more precise than earlier measurements by conventional techniques. For Ψ>0, we found that the pattern close to onset consisted of squares. Our data give the threshold of convection rc≡Rc/Rc0 (Rc is the critical Rayleigh number of the mixture and Rc0 that of the pure fluid) from measurements of the refractive-index power of the pattern as revealed by a very sensitive quantitative shadowgraph method. Over the range Ψ<~0.011, corresponding to rc>~0.2, these results are in good agreement with linear stability analysis. The measured refractive-index power varies by six orders of magnitude as a function of r and for r>~0.55 is in reasonable agreement with predictions based on the ten-mode Lorenz-like Galerkin truncation of Müller and Lücke [H. W. Müller and M. Lücke, Phys. Rev. A 38, 2965 (1988)]. For smaller r, the model predicts a cancellation between contributions to the refractive index from concentration and temperature variations, which does not seem to occur in the physical system. Determinations of the wave numbers of the patterns near onset are consistent with the theoretically predicted small critical wave numbers at positive Ψ. As r approaches one, we find that q approaches the critical wave number qc0~=3 of the pure fluid. (c) 1995 The American Physical Society

  14. Stability of LS and LS2 crystal structures in binary mixtures of hard and charged spheres

    NASA Astrophysics Data System (ADS)

    Hynninen, A.-P.; Filion, L.; Dijkstra, M.

    2009-08-01

    We study by computer simulations the stability of various crystal structures in a binary mixture of large and small spheres interacting either with a hard sphere or a screened-Coulomb potential. In the case of hard-core systems, we consider structures that have atomic prototypes CrB, γCuTi, αIrV, HgBr2, AuTe2, Ag2Se and the Laves phases (MgCu2, MgNi2, and MgZn2) as well as a structure with space group symmetry 74. By utilizing Monte Carlo simulations to calculate Gibbs free energies, we determine composition versus pressure and constant volume phase diagrams for diameter ratios of q =0.74, 0.76, 0.8, 0.82, 0.84, and 0.85 for the small and large spheres. For diameter ratios 0.76≤q≤0.84, we find the Laves phases to be stable with respect to the other crystal structures that we considered and the fluid mixture. By extrapolating to the thermodynamic limit, we show that the MgZn2 structure is the most stable one of the Laves structures. We also calculate phase diagrams for equally and oppositely charged spheres for size ratio of 0.73 taking into consideration the Laves phases and CsCl. In the case of equally charged spheres, we find a pocket of stable Laves phases, while in the case of oppositely charged spheres, Laves phases are found to be metastable with respect to the CsCl and fluid phases.

  15. Interplay between crystallization and glass transition in binary Lennard-Jones mixtures

    NASA Astrophysics Data System (ADS)

    Banerjee, Atreyee; Chakrabarty, Suman; Bhattacharyya, Sarika Maitra

    2013-09-01

    In this work we explore the interplay between crystallization and glass transition in different binary mixtures by changing their inter-species interaction length and also the composition. We find that only those systems which form bcc crystal in the equimolar mixture and whose global structure for larger xA (xA = 0.6, where xA is the mole fraction of the bigger particles) is a mixed fcc + bcc phase, do not crystallize at this higher composition. However, the systems whose equimolar structure is a variant of fcc (NaCl type crystal) and whose global structure at larger xA is a mixed NaCl + fcc phase, crystallize easily to this mixed structure. We find that the stability against crystallization of this "bcc zone" is due to the frustration between the locally preferred structure (LPS) and the mixed bcc + fcc crystal. Our study suggests that when the global structure is a mixed crystal where a single species contributes to both the crystal forms and where the two crystal forms have large difference in some order parameter related to that species then this induces frustration between the LPS and the global structure. This frustration makes the systems good glass former. When xA is further increased (0.70 ⩽ xA < 0.90) the systems show a tendency towards mixed fcc crystal formation. However, the "bcc zone" even for this higher composition is found to be sitting at the bottom of a V shaped phase diagram formed by two different variants of the fcc crystal structure, leading to its stability against crystallization.

  16. Interplay between crystallization and glass transition in binary Lennard-Jones mixtures.

    PubMed

    Banerjee, Atreyee; Chakrabarty, Suman; Bhattacharyya, Sarika Maitra

    2013-09-14

    In this work we explore the interplay between crystallization and glass transition in different binary mixtures by changing their inter-species interaction length and also the composition. We find that only those systems which form bcc crystal in the equimolar mixture and whose global structure for larger x(A) (x(A) = 0.6, where x(A) is the mole fraction of the bigger particles) is a mixed fcc + bcc phase, do not crystallize at this higher composition. However, the systems whose equimolar structure is a variant of fcc (NaCl type crystal) and whose global structure at larger x(A) is a mixed NaCl + fcc phase, crystallize easily to this mixed structure. We find that the stability against crystallization of this "bcc zone" is due to the frustration between the locally preferred structure (LPS) and the mixed bcc + fcc crystal. Our study suggests that when the global structure is a mixed crystal where a single species contributes to both the crystal forms and where the two crystal forms have large difference in some order parameter related to that species then this induces frustration between the LPS and the global structure. This frustration makes the systems good glass former. When x(A) is further increased (0.70 ≤ x(A) < 0.90) the systems show a tendency towards mixed fcc crystal formation. However, the "bcc zone" even for this higher composition is found to be sitting at the bottom of a V shaped phase diagram formed by two different variants of the fcc crystal structure, leading to its stability against crystallization.

  17. Five different spectrophotometric methods for determination of Amprolium hydrochloride and Ethopabate binary mixture.

    PubMed

    Hussein, Lobna A; Magdy, N; Abbas, Mahmoud M

    2015-03-05

    Five simple, specific, accurate and precise UV-spectrophotometric methods are adopted for the simultaneous determination of Amprolium hydrochloride (AMP) and Ethopabate (ETH), a binary mixture with overlapping spectra, without preliminary separation. The first method is first derivative of the ratio spectra ((1)DD) for determination of AMP and ETH at 234.7nm and 306.8nm respectively with mean percentage recoveries 99.76±0.907 and 100.29±0.842 respectively. The second method is the mean centering of the ratio spectra for determination of AMP and ETH at 238.8nm and 313nm respectively with mean percentage recoveries 100.26±1.018 and 99.94±1.286 respectively. The third method is based on dual wavelength selection for determination of AMP and ETH at 235.3nm & 308nm and 244nm & 268.4nm respectively with mean percentage recoveries 99.30±1.097 and 100.03±1.065 respectively. The fourth method is ratio difference method for determination of AMP and ETH at 239nm & 310nm and 239nm & 313nm respectively with mean percentage recoveries 99.27±0.892 and 100.40±1.814 respectively. The fifth one is area under the curve (AUC) method where the areas between 235.6-243nm and 268.3-275nm are selected for determination of AMP and ETH with mean percentage recoveries 100.35±1.031 and 100.39±0.956 respectively. These methods are tested by analyzing synthetic mixtures of the two drugs and they are applied to their pharmaceutical veterinary preparation. Methods are validated according to the ICH guidelines and accuracy, precision and repeatability are found to be within the acceptable limit.

  18. Influence of Molecular Structure on the Ideality of Mixing in Micelles Formed in Binary Mixtures of Surface-Active Drugs.

    PubMed

    Taboada; Attwood; Ruso; García; Sarmiento; Mosquera

    1999-08-15

    The influence of the structure of the hydrophobic group on the ideality of mixing in binary mixtures of surface active molecules has been investigated using combinations of amphiphilic penicillins. Critical concentrations (cc) of the binary mixtures of these anionic surfactants were determined by conductivity measurements as a function of the composition. The nonideality of mixing was evaluated using a regular solution approximation and expressed in terms of the interaction parameter, beta. Mixing in micelles formed in binary mixtures of the structurally similar penicillins cloxacillin, dicloxacillin, and flucloxacillin was ideal (beta = 0). In contrast, the combination of either cloxacillin or dicloxacillin with the penicillin nafcillin produced mixed micelles in which the mixing deviated from ideality (beta = +0.1 to +0.2). The positive values of beta for these systems indicated negative synergism between components of the mixtures that may be a consequence of the marked structural differences between the hydrophobic groups of these drugs. The composition of the mixed micelles was derived from the cc data by application of a theoretical treatment based on excess thermodynamic quantities. Copyright 1999 Academic Press.

  19. A rapid Fourier transform infrared spectroscopic method for analysis of certain proton pump inhibitors in binary and ternary mixtures.

    PubMed

    Khashaba, Pakinaz Y; Ali, Hassan Refat H; El-Wekil, Mohamed M

    2017-09-05

    A simple and non-destructive FTIR method was used to determine certain proton pump inhibitors (PPIs) in binary and ternary mixtures. Proton pump inhibitors (PPIs); omeprazole (OMZ), esomeprazole (EZM), lansoprazole (LAN), pantoprazole sodium (PAN sodium) and rabeprazole sodium (RAB sodium) in binary mixture with domperidone (DOM) and ternary mixture of OMZ, clarithromycin (CLM) and tinidazole (TNZ) were determined in the solid-state by FTIR spectroscopy for the first time. The method was validated according to ICH-guidelines where linearity was ranged from 20 to 850μg/g and 20-360μg/g for PPIs and DOM, respectively in binary mixtures and 10-400, 100-8000 and 150-14,000μg/g for OMZ, CLM and TNZ, respectively. Limits of detection were found to be 6-100 and 9-100μg/g for PPIs and DOM, respectively and 4, 40 and 50μg/g for OMZ, CLM and TNZ, respectively. The method was applied successfully for determination of the cited drugs in their respective pharmaceutical dosage forms. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. 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).

  1. Study on the Interaction Coefficients in PR Equation with vdW Mixing Rules for HFC and HC Binary Mixtures

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Xin; Hu, Peng; Chen, Ze-Shao

    2008-12-01

    The Peng-Robinson equation of state with the van der Waals mixing rules was used to correlate vapor-liquid equilibrium (VLE) data for HFC/HC, HFC/HFC, and HC/HC binary mixtures. The interaction parameter k ij was obtained for every binary mixture. It was assumed that k ij has contributions from the two components, and each component has its own constant contribution factor k i for the mixture, and the values of k ij indicate the degree in difference of properties between the two components. Therefore, the interaction parameters k ij is proposed as: k ij = k i - k j . The values of the mixing factor k i for Hydrofluorocarbons (HFCs) and Hydrocarbons (HCs), including propane, isobutane, n-butane, R23, R32, R125, R143a, R134a, R152a, R227ea R236fa, R236ea, and R245fa, were obtained by least-square fitting. In total, 39 refrigerant binary mixtures were analyzed on the basis of this method, and the results showed good agreement with experimental data. The overall average absolute deviations of pressure and vapor mole fraction are 1.3 % and 0.0089, respectively.

  2. Isotropic-nematic phase equilibria of hard-sphere chain fluids-Pure components and binary mixtures.

    PubMed

    Oyarzún, Bernardo; van Westen, Thijs; Vlugt, Thijs J H

    2015-02-14

    The isotropic-nematic phase equilibria of linear hard-sphere chains and binary mixtures of them are obtained from Monte Carlo simulations. In addition, the infinite dilution solubility of hard spheres in the coexisting isotropic and nematic phases is determined. Phase equilibria calculations are performed in an expanded formulation of the Gibbs ensemble. This method allows us to carry out an extensive simulation study on the phase equilibria of pure linear chains with a length of 7 to 20 beads (7-mer to 20-mer), and binary mixtures of an 8-mer with a 14-, a 16-, and a 19-mer. The effect of molecular flexibility on the isotropic-nematic phase equilibria is assessed on the 8-mer+19-mer mixture by allowing one and two fully flexible beads at the end of the longest molecule. Results for binary mixtures are compared with the theoretical predictions of van Westen et al. [J. Chem. Phys. 140, 034504 (2014)]. Excellent agreement between theory and simulations is observed. The infinite dilution solubility of hard spheres in the hard-sphere fluids is obtained by the Widom test-particle insertion method. As in our previous work, on pure linear hard-sphere chains [B. Oyarzún, T. van Westen, and T. J. H. Vlugt, J. Chem. Phys. 138, 204905 (2013)], a linear relationship between relative infinite dilution solubility (relative to that of hard spheres in a hard-sphere fluid) and packing fraction is found. It is observed that binary mixtures greatly increase the solubility difference between coexisting isotropic and nematic phases compared to pure components.

  3. Isotropic-nematic phase equilibria of hard-sphere chain fluids—Pure components and binary mixtures

    NASA Astrophysics Data System (ADS)

    Oyarzún, Bernardo; van Westen, Thijs; Vlugt, Thijs J. H.

    2015-02-01

    The isotropic-nematic phase equilibria of linear hard-sphere chains and binary mixtures of them are obtained from Monte Carlo simulations. In addition, the infinite dilution solubility of hard spheres in the coexisting isotropic and nematic phases is determined. Phase equilibria calculations are performed in an expanded formulation of the Gibbs ensemble. This method allows us to carry out an extensive simulation study on the phase equilibria of pure linear chains with a length of 7 to 20 beads (7-mer to 20-mer), and binary mixtures of an 8-mer with a 14-, a 16-, and a 19-mer. The effect of molecular flexibility on the isotropic-nematic phase equilibria is assessed on the 8-mer+19-mer mixture by allowing one and two fully flexible beads at the end of the longest molecule. Results for binary mixtures are compared with the theoretical predictions of van Westen et al. [J. Chem. Phys. 140, 034504 (2014)]. Excellent agreement between theory and simulations is observed. The infinite dilution solubility of hard spheres in the hard-sphere fluids is obtained by the Widom test-particle insertion method. As in our previous work, on pure linear hard-sphere chains [B. Oyarzún, T. van Westen, and T. J. H. Vlugt, J. Chem. Phys. 138, 204905 (2013)], a linear relationship between relative infinite dilution solubility (relative to that of hard spheres in a hard-sphere fluid) and packing fraction is found. It is observed that binary mixtures greatly increase the solubility difference between coexisting isotropic and nematic phases compared to pure components.

  4. Identification and quantification of individual volatile organic compounds in a binary mixture by SAW multisensor array and pattern recognition analysis

    NASA Astrophysics Data System (ADS)

    Penza, M.; Cassano, G.; Tortorella, F.

    2002-06-01

    We have developed a surface acoustic wave (SAW) multisensor array with five acoustic sensing elements configured as two-port resonator 433.92 MHz oscillators and a reference SAW element to recognize different individual components and determine their concentrations in a binary mixture of volatile organic compounds (VOCs) such as methanol and acetone, in the ranges 15-130 and 50-250 ppm, respectively. The SAW sensors have been specifically coated by various sensing thin films such as arachidic acid, carbowax, behenic acid, triethanolamine or acrylated polysiloxane, operating at room temperature. By using the relative frequency change as the output signal of the SAW multisensor array with an artificial neural network (ANN), a recognition system has been realized for the identification and quantification of tested VOCs. The features of the SAW multisensor array exposed to a binary component organic mixture of methanol and acetone have been extracted from the output signals of five SAW sensors by pattern recognition (PARC) techniques, such as principal component analysis (PCA). An organic vapour pattern classifier has been implemented by using a multilayer neural network with a backpropagation learning algorithm. The normalized responses of a reduced set of SAW sensors or selected principal components scores have been used as inputs for a feed-forward multilayer perceptron (MLP), resulting in a 70% correct recognition rate with the normalized responses of the four SAW sensors and in an enhanced 80% correct recognition rate with the first two principal components of the original data consisting of the normalized responses of the four SAW sensors. The prediction of the individual vapour concentrations has been tackled with PCA for features extraction and by using the first two principal components scores as inputs to a feed-forward MLP consisting of a gating network, which decides which of three specific subnets should be used to determine the output concentration: the

  5. Classical binary nucleation theory applied to the real mixture n-nonane/methane at high pressures

    NASA Astrophysics Data System (ADS)

    Looijmans, K. N. H.; Luijten, C. C. M.; Hofmans, G. C. J.; van Dongen, M. E. H.

    1995-03-01

    A thermodynamic model of the formation free energy of a droplet, based on a real equation of state, has been implemented in the binary classical nucleation theory to analyze homogeneous nucleation of mixtures of n-nonane and methane in the coexistence region at high pressures. The composition of the critical nucleus is computed by solving the Kelvin equations, the chemical potentials, and molar volumes being evaluated from the Redlich-Kwong-Soave equation of state. Real gas behavior appears to have a strong effect on nucleation due to mutual interactions between methane and nonane molecules. Numerical calculations show an increasing concentration of methane in critical clusters with increasing pressure at fixed temperature and supersaturation. As a consequence, the surface tension of the critical droplets, which is evaluated by means of the Parachor method, is lowered, having a strong increasing effect on the nucleation rate; a 10 bar increase of total pressure leads to an increase of the nucleation rate of several orders of magnitude.

  6. Thermal conductivity, shear and bulk viscosities for a relativistic binary mixture

    NASA Astrophysics Data System (ADS)

    Moratto, Valdemar; Kremer, Gilberto M.

    2016-11-01

    In the present work, we deal with a binary mixture of diluted relativistic gases within the framework of the kinetic theory. The analysis is made within the framework of the Boltzmann equation. We assume that the gas is under the influence of an isotropic Schwarzschild metric and is composed of particles with speeds comparable with the light speed. Taking into account the constitutive equations for the laws of Fourier and Navier-Stokes, we obtain expressions for the thermal conductivity, the shear, and bulk viscosities. To evaluate the integrals we assume a hard-sphere interaction along with non-disparate masses for the particles of each component. We show the analytical expressions and the behavior of the transport coefficients with respect to a relativistic parameter which gives the ratio of the rest energy of the particles to the thermal energy of the gas. We also determine the dependence of the transport coefficients with respect to the gravitational potential and demonstrate that the corresponding one component limit is recovered by considering particles with equal masses, in accordance with the kinetic theory of a single fluid.

  7. Simulations of a binary-sized mixture of inelastic grains in rapid shear flow.

    PubMed

    Clelland, R; Hrenya, C M

    2002-03-01

    In an effort to explore the rapid flow behavior associated with a binary-sized mixture of grains and to assess the predictive ability of the existing theory for such systems, molecular-dynamic simulations have been carried out. The system under consideration is composed of inelastic, smooth, hard disks engaged in rapid shear flow. The simulations indicate that nondimensional stresses decrease with an increase in d(L)/d(S) (ratio of large particle diameter to small particle diameter) or a decrease in nu(L)/nu(S) (area fraction ratio), as is also predicted by the kinetic theory of Willits and Arnarson [Phys. Fluids 11, 3116 (1999)]. Furthermore, the level of quantitative agreement between the theoretical stress predictions and simulation data is good over the entire range of parameters investigated. Nonetheless, the molecular-dynamic simulations also show that the assumption of an equipartition of energy rapidly deteriorates as the coefficient of restitution is decreased. The magnitude of this energy difference is found to increase with the difference in particle sizes.

  8. Microwave dielectric relaxation spectroscopy study of propylene glycol/ethanol binary mixtures: Temperature dependence.

    PubMed

    Vishwam, T; Shihab, Suriya; Murthy, V R K; Tiong, Ha Sie; Sreehari Sastry, S

    2017-05-15

    Complex dielectric permittivity measurements of propylene glycol (PG) in ethanol at various mole fractions were measured by using open-ended coaxial probe technique at different temperatures in the frequency range 0.02<ν/GHz<20. The dipole moment (μ), excess dipole moment (Δμ),excess permittivity (ε(E)), excess inverse relaxation time(1/τ)(E), Bruggeman parameter (fB), excess Helmholtz energy (ΔF(E)) are determined using experimental data. From the minimum energy based geometry optimization, dipole moments of individual monomers of propylene glycol and ethanol and their binary system have been evaluated theoretically at gaseous state as well as alcoholic medium by using PCM and IEFPCM solvation models from the Hatree-Fock (HF) and Density Functional Theory (DFT-B3LYP) methods with 6-311G* and 6-311G** basis sets. The obtained results have been interpreted in terms of the short and long range ordering of the dipoles, Kirkwood correlation factor (g(eff)), thermodynamic parameters, mean molecular polarizability (αM) and interaction in the mixture through hydrogen bonding.

  9. Effect of Glycerol Water Binary Mixtures on the Structure and Dynamics of Protein Solutions

    SciTech Connect

    Ghattyvenkatakrishna, Pavan K; Carri, Gustavo A.

    2014-01-01

    We have performed 20ns of fully atomistic molecular dynamics simulations of Hen Egg-White Lysozyme in 0, 10, 20, 30 and 100% by weight of glycerol in water to better understand the microscopic physics behind the bioprotection offered by glycerol to naturally occuring biological systems. The sovlent exposure of protein surface residues changes when glycerol is introduced. The dynamic behavior of the protein, as quantified by the Incoherent Intermediate Scattering Function, shows a non-monotonic dependence on glycerol content. The fluctuations of the protein residues with respect to each other were found to be similar in all water containing solvents; but different from the pure glycerol case. The increase in the number of protein glycerol hydrogen bonds in glycerol water binary mixtures explains the slowing down of protein dynamics as the glycerol content increases. We also explored the dynamic behavior of the hydration layer. We show that the short-length scale dynamics of this layer are insenstive to glycerol concentration. However, the long-length scale behavior shows a significant dependence on glycerol content. We also provide insights into the behavior of bound and mobile water molecules.

  10. 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.

  11. 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.

  12. Benchmark solutions for transport in d-dimensional Markov binary mixtures

    NASA Astrophysics Data System (ADS)

    Larmier, Coline; Hugot, François-Xavier; Malvagi, Fausto; Mazzolo, Alain; Zoia, Andrea

    2017-03-01

    Linear particle transport in stochastic media is key to such relevant applications as neutron diffusion in randomly mixed immiscible materials, light propagation through engineered optical materials, and inertial confinement fusion, only to name a few. We extend the pioneering work by Adams, Larsen and Pomraning [1] (recently revisited by Brantley [2]) by considering a series of benchmark configurations for mono-energetic and isotropic transport through Markov binary mixtures in dimension d. The stochastic media are generated by resorting to Poisson random tessellations in 1 d slab, 2 d extruded, and full 3 d geometry. For each realization, particle transport is performed by resorting to the Monte Carlo simulation. The distributions of the transmission and reflection coefficients on the free surfaces of the geometry are subsequently estimated, and the average values over the ensemble of realizations are computed. Reference solutions for the benchmark have never been provided before for two- and three-dimensional Poisson tessellations, and the results presented in this paper might thus be useful in order to validate fast but approximated models for particle transport in Markov stochastic media, such as the celebrated Chord Length Sampling algorithm.

  13. Information content in fluorescence correlation spectroscopy: binary mixtures and detection volume distortion.

    PubMed

    Lam, Jonathan D; Culbertson, Michael J; Skinner, Nathan P; Barton, Zachary J; Burden, Daniel L

    2011-07-01

    When properly implemented, fluorescence correlation spectroscopy (FCS) reveals numerous static and dynamic properties of molecules in solution. However, complications arise whenever the measurement scenario is complex. Specific limitations occur when the detection region does not match the ideal Gaussian geometry ubiquitously assumed by FCS theory, or when properties of multiple fluorescent species are assessed simultaneously. A simple binary solution of diffusers, where both mole fraction and diffusion constants are sought, can face interpretive difficulty. In order to better understand the limits of FCS, this study systematically explores the relationship between detection-volume distortion, diffusion constants, species mole fraction, and fitting methodology in analyses that utilize a two-component autocorrelation model. FCS measurements from solution mixtures of dye-labeled protein and free dye are compared to simulations, which predict the performance of FCS under a variety of experimental circumstances. The results reveal a range of conditions necessary for performing accurate measurements and describe experimental scenarios that should be avoided. The findings also provide guidelines for obtaining meaningful measurements when grossly distorted detection volumes are utilized and generally assess the latent information contained in FCS datasets.

  14. Quantum properties of a binary bosonic mixture in a double well

    NASA Astrophysics Data System (ADS)

    Mujal, Pere; Juliá-Díaz, Bruno; Polls, Artur

    2016-04-01

    This work contains a detailed analysis of the properties of the ground state of a two-component two-site Bose-Hubbard model, which captures the physics of a binary mixture of Bose-Einstein condensates trapped in a double-well potential. The atom-atom interactions within each species and among the two species are taken as variable parameters, while the hopping terms are kept fixed. To characterize the ground state, we use observables such as the imbalance of population and its quantum uncertainty. The quantum many-body correlations present in the system are further quantified by studying the degree of condensation of each species, the entanglement between the two sites, and the entanglement between the two species. The latter is measured by means of the Schmidt gap, the von Neumann entropy, or the purity obtained after tracing out a part of the system. A number of relevant states are identified, e.g., Schrödinger catlike many-body states, in which the outcome of the population imbalance of both components is completely correlated, and other states with even larger von Neumann entropy which have a large spread in Fock space.

  15. Hysteresis and the Cholesterol Dependent Phase Transition in Binary Lipid Mixtures with the Martini Model.

    PubMed

    Arnarez, Clement; Webb, Alexis; Rouvière, Eric; Lyman, Edward

    2016-12-29

    Extensive Martini simulation data, totaling 5 ms, is presented for binary mixtures of dipalmitoylphosphatidylcholine (DPPC) and cholesterol. Using simulation initiated from both gel (so) and liquid-disordered (Ld) phases, significant and strongly cholesterol-dependent hysteresis in the enthalpy as a function of temperature is observed for cholesterol mole fractions from 0 to 20 mol %. Although the precise phase transition temperature cannot be determined due to the hysteresis, the data are consistent with a first order gel to fluid transition, which increases in temperature with cholesterol. At 30 mol % cholesterol, no hysteresis is observed, and there is no evidence for a continuous transition, in either structural parameters like the area per lipid or in the heat capacity as a function of temperature. The results are consistent with a single uniform phase above a critical cholesterol composition between 20 and 30 mol % in Martini, while highlighting the importance and difficulty of obtaining the equilibrium averages to locate phase boundaries precisely in computational models of lipid bilayers.

  16. Evaporation dynamics of non-spherical sessile drops of pure fluids and binary mixtures

    NASA Astrophysics Data System (ADS)

    Saenz, Pedro J.; Matar, Omar K.; Sefiane, Khellil; Valluri, Prashant; Kim, Jungho

    2015-11-01

    The dynamics of pure axisymmetric volatile sessile droplets have been meticulously examined over the last four decades but remain poorly understood. Studies focusing on more realistic non-spherical configurations are virtually non-existent. The dynamics of the latter are examined in this investigation by means of experiments and numerical simulations. We show that the lifetime and bulk flow characteristics of these drops depend on their size and shape. The irregular geometries lead to the emergence preferential convection currents in the liquid as well as differential local evaporation rates noticeable along the contact line. Similarly, we inspect the thermocapillary stability of the flow, which results as the liquid volatility increases, and find that this is also affected by the non-uniform wettability along the triple line. The Marangoni-driven instabilities grow in an intricate spatio-temporal fashion leading to the emergence of different flow regimes. Finally, we also provide new insights into the evaporation process of binary-mixture drops. Memphis Multiphase (EPSRC EP/K003976/1) & ThermaPOWER (EU IRSES-PIRSES GA-2011-294905).

  17. 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.

  18. Validation of different spectrophotometric methods for determination of vildagliptin and metformin in binary mixture

    NASA Astrophysics Data System (ADS)

    Abdel-Ghany, Maha F.; Abdel-Aziz, Omar; Ayad, Miriam F.; Tadros, Mariam M.

    New, simple, specific, accurate, precise and reproducible spectrophotometric methods have been developed and subsequently validated for determination of vildagliptin (VLG) and metformin (MET) in binary mixture. Zero order spectrophotometric method was the first method used for determination of MET in the range of 2-12 μg mL-1 by measuring the absorbance at 237.6 nm. The second method was derivative spectrophotometric technique; utilized for determination of MET at 247.4 nm, in the range of 1-12 μg mL-1. Derivative ratio spectrophotometric method was the third technique; used for determination of VLG in the range of 4-24 μg mL-1 at 265.8 nm. Fourth and fifth methods adopted for determination of VLG in the range of 4-24 μg mL-1; were ratio subtraction and mean centering spectrophotometric methods, respectively. All the results were statistically compared with the reported methods, using one-way analysis of variance (ANOVA). The developed methods were satisfactorily applied to analysis of the investigated drugs and proved to be specific and accurate for quality control of them in pharmaceutical dosage forms.

  19. Parametric study on phase separation of binary mixtures in a lid driven cavity: A DPD study

    NASA Astrophysics Data System (ADS)

    Gidituri, Harinadha; Anand, Vijay; Panchagnula, Mahesh; Vedantam, Srikanth

    2016-11-01

    We investigate the phase separation behavior of binary mixtures in two dimensional periodic and lid driven cavity domains using dissipative particle dynamics (DPD). The effect of DPD parameters like repulsion coefficient, dissipative coefficient, cut-off radius, and weight function exponent on domain size growth has been studied. The phase separation is delayed for low values of repulsion coefficient. Under these conditions, a few clusters of the dispersed phase are distributed in a continuous phase. This is because of weak inter-particle repulsion. As we increase the repulsion coefficient value, this behavior disappears. The domain growth rate is also observed to increase with an increase in the value of the dissipation coefficient as well as cut-off radius. Finally, the dynamics of phase separation in the lid driven cavity problem are significantly different when compared to that in the periodic domain, due to the formation of a stable vortex in the cavity. The vortex results in a dynamic equilibrium between clustering and separation. The distribution of cluster sizes is studied as a function of the driven cavity parameters.

  20. Emergence of microstructural patterns in skin cancer: a phase separation analysis in a binary mixture

    NASA Astrophysics Data System (ADS)

    Chatelain, C.; Balois, T.; Ciarletta, P.; Ben Amar, M.

    2011-11-01

    Clinical diagnosis of skin cancers is based on several morphological criteria, among which is the presence of microstructures (e.g. dots and nests) sparsely distributed within the tumour lesion. In this study, we demonstrate that these patterns might originate from a phase separation process. In the absence of cellular proliferation, in fact, a binary mixture model, which is used to represent the mechanical behaviour of skin cancers, contains a cell-cell adhesion parameter that leads to a governing equation of the Cahn-Hilliard type. Taking into account a reaction-diffusion coupling between nutrient consumption and cellular proliferation, we show, with both analytical and numerical investigations, that two-phase models may undergo a spinodal decomposition even when considering mass exchanges between the phases. The cell-nutrient interaction defines a typical diffusive length in the problem, which is found to control the saturation of a growing separated domain, thus stabilizing the microstructural pattern. The distribution and evolution of such emerging cluster morphologies, as predicted by our model, are successfully compared to the clinical observation of microstructural patterns in tumour lesions.