Showing papers on "Binary system published in 1999"

Long-Term Stability of Planets in Binary Systems

Abstract: A simple question of celestial mechanics is investigated: in what regions of phase space near a binary system can planets persist for long times? The planets are taken to be test particles moving in the field of an eccentric binary system. A range of values of the binary eccentricity and mass ratio is studied, and both the case of planets orbiting close to one of the stars, and that of planets outside the binary orbiting the systems center of mass, are examined. From the results, empirical expressions are developed for both (1) the largest orbit around each of the stars and (2) the smallest orbit around the binary system as a whole, in which test particles survive the length of the integration (10A4 binary periods). The empirical expressions developed, which are roughly linear in both the mass ratio mu and the binary eccentricity e, are determined for the range 0.0=e=0.7-0.8 and 0.1=mu=0.9 in both regions and can be used to guide searches for planets in binary systems. After considering the case of a single low-mass planet in binary systems, the stability of a mutually interacting system of planets orbiting one star of a binary system is examined, though in less detail.

Laboratory studies of particle nucleation: Initial results for H2SO4, H2O, and NH3 vapors

Abstract: Particle formation in the binary H2SO4-H2O vapor system was studied at 295 K in a series of experiments employing a flow reactor. The concentration of H2SO4 was detected by chemical ionization mass spectrometry, and an ultrafine particle condensation nucleus counter was used to count the newly nucleated particles. Results yield a particle formation rate that is approximately proportional to [H2SO4] raised to the eighth power and to [H2O] raised to the fifth power. The power dependencies measured here are significantly different from those determined in previous experimental work, and furthermore, the water dependence is markedly different from that predicted from current theories. The effect of adding ammonia vapor to the binary system was investigated; concentrations of NH3 in the many tens of parts per trillion by volume range were observed to promote dramatically the rate of particle nucleation.

Experimental pressure-temperature data on three- and four-phase equilibria of fluid, hydrate, and ice phases in the system carbon dioxide-water

Abstract: Pressure−temperature data of three-phase lines, quadruple points, and critical end points of the binary system carbon dioxide−water were taken in a high-pressure view cell at temperatures between 270 and 305 K and pressures up to 7.4 MPa. The phase equilibria involve both fluid (liquid and vapor) phases and solid phases (hydrate and ice). The present results are in good agreement with most data from the literature. Correlations of the experimental data with Clausius−Clapeyron type equations are given. The literature data are reviewed critically in comparison to the correlations. The global phase behavior of the system carbon dioxide−water is discussed and compared to the phase behavior of similar binary systems.

Ppl 15: the first brown dwarf spectroscopic binary

Abstract: PPl 15 is the first object to have been confirmed as a brown dwarf by the lithium test (in 1995), though its inferred mass was very close to the substellar limit. It is a member of the Pleiades open cluster. Its position in a cluster color-magnitude diagram suggested that it might be binary, and preliminary indications that it is a double-lined spectroscopic binary were reported by us in 1997. Here we report on the results of a consecutive week of Keck HIRES observations of this system, which yield its orbit. It has a period of about 5.8 days, and an eccentricity of 0.4 ± 0.05. The rotation of the stars is slow for this class of objects. Because the system luminosity is divided between two objects with a mass ratio of 0.85, each of them is rendered an incontrovertible brown dwarf, with masses between 60 and 70 MJ. We show that component B is a little redder than A by studying their wavelength-dependent line ratios and that this variation is compatible with the mass ratio. We confirm that the system has lithium but cannot support the original conclusion that it is depleted (which would be surprising, given the new masses). This is a system of very close objects, which, if they had combined, would have produced a low-mass star. We discuss the implications of this discovery for the theories of binary formation and formation of very low mass objects.

Density, Viscosity, Refractive Index, and Speed of Sound in Binary Mixtures of Acrylonitrile with Methanol, Ethanol, Propan-1-ol, Butan-1-ol, Pentan-1-ol, Hexan-1-ol, Heptan-1-ol, and Butan-2-ol

Abstract: Density, viscosity, and refractive index data at 298.15, 303.15, and 308.15 K as well as the speed of sound at 298.15 K in the binary mixtures of acrylonitrile with methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, heptan-1-ol, and butan-2-ol are presented over the whole range of mixture compositions. From these results, excess molar volume, VE, deviations in viscosity, Δη, molar refraction, ΔR, speed of sound, Δu, and isentropic compressibility, ΔkS have been calculated. These quantities are fitted to a Redlich−Kister type polynomial equation to derive the binary coefficients and estimate the standard deviations between the experimental and calculated quantities.

Phase Behavior and Microstructure in Binary Block Copolymer/Selective Solvent Systems: Experiments and Theory

Abstract: A combined experimental and theoretical study of phase behavior and structure in binary systems of block copolymers and a selective solvent is presented. The block copolymers used here consist of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), and the solvent is water, selective for the PEO block. The concentration−temperature phase diagrams of (EO)8(PO)47(EO)8 (Pluronic L92) and (EO)11(PO)70(EO)11 (Pluronic L122) in water have been determined experimentally. These two block copolymers are unique in that they form both normal (H1, “oil-in-water”) and reverse (H2, “water-in-oil”) hexagonal lyotropic liquid crystalline structures in binary systems with water over the same temperature range. This is the first time the H2 structure is reported in a binary PEO−PPO−PEO/water system. Thereafter, the predicted phase diagram of (EO)20(PO)69(EO)20 in water is given, employing a self-consistent mean-field lattice theory with internal degrees of freedom. The free energy for a number of possible microstruc...

New investigations within the TeO2-WO3 system : phase equilibrium diagram and glass crystallization

Abstract: The TeO2-WO3 pseudo-binary system was investigated by temperature programmed X-ray diffraction and differential scanning calorimetry (DSC) The investigated samples were prepared by air quenching of totally or partially melted mixes of TeO2 and WO3 Glass forming compositions were identified by X-ray diffraction on quenched samples Glass transition and crystallization temperatures were measured by DSC The identification of the compounds appearing during glass crystallization revealed two new metastable compounds The first one, which appears both for low WO3 content and pure TeO2 glasses, was attributed unambiguously to a new TeO2 polymorph called γ This one irreversibly transforms into the stable α-TeO2 form, at about 510 °C It crystallizes with the orthorhombic symmetry and unit cell parameters a = 08453(3) nm, b = 04994(2) nm, c = 04302(2) nm, Z = 4 The second compound was detected for samples containing about 5 to 10 WO3 mol % It is cubic (F mode, a = 0569 nm, Z = 4) and seems to have a fluorite-like structure In addition, phase equilibrium diagram was determined This binary system appears to be a true binary eutectic one

Thermodynamic assessment of the Aluminum-Manganese (Al-Mn) binary phase diagram

Abstract: A thermodynamic calculation of the Al-Mn binary system that takes into account recent experimental results and includes five intermetallic compounds and all the solid-solution phases is presented. The Gibbs energy of the body-centered cubic (bcc) phase has been described on the basis of the two-sublattice model that includes the second-order A2/B2 ordering reaction as well. A consistent set of optimized thermodynamic parameters has been arrived at for describing the Gibbs energy of each phase in this system leading to a better fit between calculation and experiments.

Density, Viscosity, and Refractive Index for Binary Systems of n-C16 and Four Nonlinear Alkanes at 298.15 K

Abstract: This work aims at extending the characterization of binary systems containing mixtures of n-C16 with branched saturated hydrocarbons of similar, higher, and lower number of carbon atoms. The systems considered are n-C16 with isooctane (2,2,4-trimethylpentane), cyprane (2,2,4,4,6,8,8-heptamethylnonane), pristane (2,6,10,14-tetramethylpentadecane), and squalane (2,6,10,15,19,23-tetracosane). Density, viscosity, refractive index, molar refractivity, excess volume, viscosity deviation function, and refractivity deviation function at 298.15 K are reported. Measured data are correlated with semiempirical models and parameters are reported.

Density, Refractive Index, Viscosity, and Speed of Sound in Binary Mixtures of Cyclohexanone with Benzene, Methylbenzene, 1,4-Dimethylbenzene, 1,3,5-Trimethylbenzene, and Methoxybenzene in the Temperature Interval (298.15 to 308.15) K

Abstract: Experimental results of density, refractive index, and viscosity at 298.15, 303.15, and 308.15 K and speed of sound at 298.15 K are presented for the binary mixtures of cyclohexanone with benzene, ...

Vapor-liquid equilibria in the nitrogen + carbon dioxide + propane system from 240 to 330 K at pressures to 15 MPa

Abstract: Vapor−liquid equilibria were measured for the nitrogen, carbon dioxide, and propane ternary system and its constituent binaries over the temperature range 240 K to 330 K. The binary systems were measured at 240, 270, and 330 K, and the ternary system was studied at 240 K for 2.0 and 13.0 MPa, 270 K for 2.0, 6.0, and 13.0 MPa, and 330 K and 5 MPa. The Peng−Robinson equation of state was used to model the system.

Binary adsorption of copper(II) and cadmium(II) from aqueous solutions by biomass of marine alga Durvillaea potatorum

Abstract: Much work on the biosorption of heavy metals by low-cost, natural biomass has been on the uptake of single metals. In practice, wastewaters often contain multiple heavy metal ions. In this paper the binary adsorption of copper(II) and cadmium(II) by a pretreated biomass of the marine alga Durvillaea potatorum from aqueous solutions was studied. The results showed that the uptake capacities for each heavy metal of the binary system were lower when compared with the single metal biosorption for copper and cadmium, respectively, but the total capacities for the binary system were similar to those obtained for single metal biosorption. The uptake capacities for copper and cadmium increased as the equilibrium pH increased and reached a plateau at a pH around 5.0. The uptake process was relatively fast, with 90% of the adsorption completed within 10 minutes for copper and 30 minutes for cadmium, and equilibrium reached after about 60 minutes of stirring. The biosorption isotherms of binary systems were not significantly affected by equilibrium temperature. The presence of light metal ions in solution also did not affect adsorption significantly. The binary adsorption was successfully predicted by the extended Langmuir model, using parameters and capacities obtained from single component systems.

Binary protein adsorption on gel-composite ion-exchange media

Abstract: The adsorption kinetics of mixtures of lysozyme and cytochrome-C on S-HyperD-M, a cation exchanger composed of a rigid macroporous silica matrix whose pores are filled with a functionalized polyacrylamide gel, was characterized. Single-component isotherms were found to follow approximately the steric mass-action law of Brooks and Cramer, and an extension of this model to a binary system was consistent with two-component uptake equilibrium results. Transient adsorption experiments were done to investigate the kinetics of sequential and simultaneous adsorption of the two proteins. At low protein concentrations, adsorption is essentially noncompetitive, and mass transfer is controlled by the external film resistance. At higher concentrations, equilibrium becomes competitive and coupling of the intraparticle diffusion fluxes occurs. A model based on a Maxwell–Stefan approach, where the driving force for diffusion is expressed in terms of the chemical potential gradient, was in approximate agreement with the experimental results.

High-pressure solubilities of hydrogen, nitrogen, and carbon monoxide in dodecane from 344 to 410 K at pressures to 13.2 MPa

Abstract: The solubilities of hydrogen, nitrogen, and carbon monoxide in dodecane were measured using a static equilibrium cell over the temperature range from 344.3 to 410.9 K at pressures to 13.24 MPa. The uncertainty in these measurements is estimated to be less than 0.001 in mole fraction. The data are represented with root-mean-square errors of less than 0.003 mole fraction by the Soave-Redlich-Kwong and Peng-Robinson equations of state when a single empirical interaction parameter, C{sub ij}, is used for each binary system.

Heat Capacities, Excess Enthalpies, and Volumes of Mixtures Containing Cyclic Ethers. 3. Binary Systems {Tetrahydrofuran, Tetrahydropyran, 1,4-Dioxane, or 1,3-Dioxolane + Cyclohexane or Toluene}

Abstract: Excess molar volumes for {1,4-dioxane or 1,3-dioxolane + cyclohexane} and excess molar enthalpies and isobaric excess molar heat capacities for the binary mixtures {tetrahydrofuran, tetrahydropyran, 1,4-dioxane, or 1,3-dioxolane + cyclohexane or toluene} at the temperature 298.15 K have been determined as a function of mole fraction. The magnitude of these experimental quantities is discussed in terms of the nature and type of intermolecular interactions in binary mixtures. When available, the results have been compared with literature values.

Isobaric Vapor−Liquid Equilibria for 1-Propanol + Water + Calcium Nitrate

Abstract: Isobaric vapor−liquid equilibria for all of the binary and ternary mixtures of 1-propanol, water, and calcium nitrate have been measured at 100.00 kPa using a recirculating still. The addition of calcium nitrate to the solvent mixture produced an important salt effect; the azeotrope was removed at salt mole fractions higher than 0.08. The three experimental binary data sets were independently fitted with the electrolyte NRTL model (Mock, B.; Evans, L. B.; Chen, C. C. AIChE J. 1986, 32, 1655−1664), and the parameters of Mock's model were estimated for each binary system. No ternary parameter was required. These parameters were used to predict the ternary vapor−liquid equilibrium using the same model, and the values so obtained agreed well with the experimental ones.

From the Correlation of Binary Systems Involving Supercritical CO2 and Fatty Acid Esters to the Prediction of (CO2−Fish Oils) Phase Behavior

Abstract: In this paper, a purely predictive model for the phase equilibria computation of mixtures involving fatty acid esters (FAE) and supercritical carbon dioxide is proposed. In a first step, the phase equilibria modeling of FAE/CO{sub 2} binary systems were performed using the Peng-Robinson equation of state. To obtain a purely predictive model, the critical properties ({Tc}, P{sub c}) and the acentric factor ({omega}) of the FAE were estimated with specific correlations. Moreover, the group contribution method developed by Abdoul et al., which allows the prediction of binary interaction parameters (k{sub ij}), was extended to ester compounds and an additional group (the ester function) was defined. Such an approach allowed the authors to correlate with quite good accuracy all the binary FAE/CO{sub 2} systems. In a second step, dew points of (CO{sub 2}/fish oil) systems were measured and the previous model was used to check its capability in predicting these data. The fish oil under study contained 30 different fatty acid ethyl esters, and the model was able to predict with very good accuracy the measured saturation pressures.

Viscosities and Densities for Binary Mixtures of Anisole with 1-Butanol, 1-Pentanol, 1-Hexanol, 1-Heptanol, and 1-Octanol

Abstract: Densities and viscosities were measured for anisole + 1-butanol, + 1-pentanol, + 1-hexanol, + 1-heptanol, and + 1-octanol at 303.15 K, 313.15 K, and 323.15 K. The excess volumes and viscosity deviations from the mole fraction average were calculated and correlated by a Redlich−Kister type equation. While the excess volumes of anisole + 1-butanol are negative, those of the remaining binary mixtures are positive. The viscosity deviations are negative for all systems.

Densities and Viscosities of Ethylene Glycol Binary Mixtures at 293.15 K

Abstract: Densities (ρ) and viscosities (η) for the binary mixtures of ethylene glycol with 2-aminoethanol, 2-chloroethanol, 2-ethoxyethanol, benzyl alcohol, pentanol-1, methanol, cyclohexanone, and acetone have been measured over the whole composition range at 293.15 K. The excess volumes and the viscosity deviations were calculated, and the results were fitted to a Redlich−Kister type polynomial relation. The corresponding parameters have been derived. The results were interpreted in terms of specific interactions between the unlike molecules.

Thermodynamic calculation for alloy systems

Abstract: The formulas for calculating the activity coefficient, γ i, in the binary system and the activity coefficient of a solute at infinite dilution, γ 0 , as well as interaction parameters, e i i and e i j , in a metallic melt have been proposed on the basis of Miedema et al.’s model for the estimation of the heat of formation of binary alloys. The formulas can be used in both solid and liquid solutions and have been used in the calculation of both binary and ternary alloy systems taken from 75 elements. The results were compared with the experimental values.