Showing papers on "Binary system published in 2021"

Removal of Congo red from aqueous solution in single and binary mixture systems using Argan nutshell wood

Abstract: Purpose Argan nutshell wood (ANW) has been used in this study as an agricultural solid waste to remove Congo red (CR) from an aqueous solution in single and mixture binary in the presence of methylene blue (MB) or crystal violet (CV). Design/methodology/approach The ANW was characterized by Fourier transform infrared and scanning electron microscope analysis. The effect of ANW dose (8–40 gL−1), contact time (0–180 min), pH of the solution (4–11) and CR dye concentration (100–500 mgL−1) on CR adsorption was studied in batch mode and evaluated by kinetic and isotherm models in a single system. In the binary system, the CR removal was studied from a CR + MB and CR + CV mixture with different percentages of dyes, ranging from 0% to 100%. Findings The pseudo-second-order and the Langmuir models could best describe the CR sorption onto ANW in a single system. In addition, in the case of the binary system, there is the appearance of a synergistic phenomenon between the CR and the other cationic dyes and the CR adsorption capacity increased until 12.24 mg g-1 and 12.06 mg g-1 in the presence of the MB and CV in the mixture, respectively. Practical implications This study demonstrated that ANW prepared can be suggested as an excellent potential adsorbent to remove dyes from wastewaters from single and mixture systems. Originality/value This study is original.

Mathematical modeling of crystallization process from a supercooled binary melt

Abstract: The article is concerned with the analytical solution to the integro-differential system of balance and kinetic equations that describe the crystal growth phenomenon in a binary system for various nucleation kinetics. The effect of impurity concentration on the evolutionary behavior of crystals is shown. The nonlinear dynamics of a supercooled binary melt is studied with allowance for the withdrawal mechanism of product crystals from a metastable liquid of the crystallizer.

Swelling and dissolution of cellulose in binary systems of three ionic liquids and three co-solvents

Abstract: The dissolution of cellulose is a critical step for the efficient utilization of this renewable resource as a starting material for high value-added chemical and biofuel production. In this study, three aprotic solvents were chosen to couple with three ionic liquids (ILs) as binary solvent systems for cellulose dissolution. The percentage of dissolved cellulose of each IL/co-solvent was evaluated and the crystallinity index (CrI) of the undissolved cellulose residues after dissolution were investigated by XRD. Dimethyl sulfoxide exhibited the most effective synergistic interaction with the ILs among three co-solvents for cellulose dissolution. In general, the higher percentage of dissolved cellulose of the IL/co-solvent binary system, the lower CrI value of the undissolved cellulose residue after dissolution. In addition, the dissolution of cellulosic materials with different crystallinity and degree of polymerization indicated that the crystallinity of a cellulosic material played a more dominating role than degree of polymerization in its dissolution process. The hydrogen bond basicity (β value) of selected IL/co-solvent binary system was also calculated. The results showed that the β value of a binary IL/co-solvent system exhibited different trend than neat IL in terms of the cellulose dissolution ability, which should be attributed to the co-solvent effect.

The eclipsing binary systems with δ Scuti component – I. KIC 10661783

Abstract: We present a comprehensive study of the eclipsing binary system KIC 10661783. The analysis of the whole Kepler light curve, corrected for the binary effects, reveals a rich oscillation spectrum with 590 significant frequency peaks, 207 of which are independent. In addition to typical $\delta$ Sct frequencies, we find small-amplitude signals in the low-frequency range that, most probably, are a manifestation of gravity-mode pulsations. We perform binary-evolution computations for this system in order to find an acceptable model describing its current stage. Our models show that the binary KIC 10661783 was formed by a rapid, almost conservative, mass transfer that heavily affected the evolution of both components in the past. One of the most important effects of binary evolution is the enormous enrichment of the outer layers of the main component with helium. This fact profoundly influences the pulsational properties of $\delta$ Scuti star models. For the first time, we demonstrate the effect of binary evolution on pulsational instability. We construct pulsational models of the main component in order to account for the mode instability of the observed frequencies. Whereas the single-star evolution model is pulsational stable in the whole frequency range, its binary-evolution counterpart has unstable modes, both, in high and low-frequency range. However, to obtain instability in almost a whole range of the observed frequencies, the modification of the mean opacity at the depth corresponding to temperatures log T = 4.69 K and log T = 5.06 K was necessary.

Thermodynamics and Intermolecular Interactions of Nicotinamide in Neat and Binary Solutions: Experimental Measurements and COSMO-RS Concentration Dependent Reactions Investigations.

Abstract: In this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential scanning calorimetry was used to characterize the fusion thermodynamics of nicotinamide. In particular, the heat capacity change upon melting was measured. The experimental data were interpreted by means of COSMO-RS-DARE (conductor-like screening model for realistic solvation–dimerization, aggregation, and reaction extension) for concentration dependent reactions. The solute–solute and solute–solvent intermolecular interactions were found to be significant in all of the studied systems, which was proven by the computed mutual affinity of the components at the saturated conditions. The values of the Gibbs free energies of pair formation were derived at an advanced level of theory (MP2), including corrections for electron correlation and zero point vibrational energy (ZPE). In all of the studied systems the self-association of nicotinamide was found to be a predominant intermolecular complex, irrespective of the temperature and composition of the binary system. The application of the COSMO-RS-DARE approach led to a perfect match between the computed and measured solubility data, by optimizing the parameter of intermolecular interactions.

The thermodynamic reassessment of the binary Al–Cu system

Abstract: The Al–Cu binary system has been investigated intensively in the past as key binary system for many important industrial alloys. With respect to new experimental results about phase equilibria in Al–Cu system, it was found necessary to prepare new CALPHAD-type thermodynamic description of the Al–Cu system. In course of this work, the known crystallography of several intermetallic phases and the information about site occupations in particular crystallographic positions were implemented in the new thermodynamic phase descriptions. The intermetallic phases were furthermore modelled with all their different temperature modifications. Very good agreement with the experimental results was reached both, for the Al–Cu phase diagram and for the calculated thermodynamic properties, namely the enthalpy of mixing, enthalpies of formation and thermodynamic activities.

Confirming NGC 6231 as the parent cluster of the runaway high-mass X-ray binary HD 153919/4U 1700-37 with Gaia DR2

Abstract: Context. A significant fraction (10–20%) of the most massive stars move through space with a high (v ≳ 30 km s−1 ) velocity. One of the possible physical explanations is that a supernova in a compact binary system results in a high recoil velocity of the system. If the system remains bound, it can be subsequently observed as a spectroscopic binary (SB1), a high-mass X-ray binary, a compact binary, and finally a gravitational-wave event.Aims. If such a system is traced back to its parent cluster, binary evolution models can be tested in great detail.Methods. The Gaia proper motions and parallaxes are used to demonstrate that the high-mass X-ray binary HD 153919/4U 1700-37 originates from NGC 6231, the nucleus of the OB association Sco OB1.Results. The O supergiant and its compact companion, of which the physical nature (a neutron star or a black hole) is unknown, move with a space velocity of 63 ± 5 km s−1 with respect to NGC 6231. The kinematical age of the system is 2.2 ± 0.1 Myr. The parallaxes and accurate proper motions in Gaia DR2 were used to perform a membership analysis of NGC 6231; 273 members are identified, of which 268 have good quality photometry. The distance to NGC 6231 is 1.63 ± 0.15 kpc. Isochrone fitting results in an age of 4.7 ± 0.4 Myr and an extinction A V to the cluster of 1.7 ± 0.1. With the identification of NGC 6231 as the parent cluster, the upper limit on the age of the progenitor of 4U1700-37 at the moment of the supernova explosion is 3.0 ± 0.5 Myr.Conclusions. With these constraints, the evolutionary history of the system can be reconstructed with an initial mass of the progenitor of the compact object > 60 M ⊙ . The high mass, the extreme mass ratio, and short orbital separation of the system make it difficult to produce possible progenitor systems through population synthesis. We propose that the system experienced a Case A mass transfer phase before the supernova, which typically widens a binary. In order to create a progenitor system that does not merge, a lot of angular momentum must be lost from the system during the phase of mass transfer and/or an asymmetry in the supernova explosion provides a kick resulting in the observed orbital parameters. Given its current high space velocity and the derived evolutionary history, the compact object in the system is more likely to have received a large natal kick, which suggests that it is more likely a neutron star than a black hole. HD 153919/4U1700-37 might be a prototype in the Milky Way for the progenitor of gravitational wave events such as GW190412.

Investigation on solid-liquid equilibrium for trifluoromethane (R23) plus difluoromethane (R32) binary system

Abstract: In this paper, an experimental apparatus based on a Calvet calorimeter (SETARAM BT215) was setup to measure the solid – liquid equilibrium for trifluoromethane (R23) plus difluoromethane (R32) binary system The melting points of some pure alkanes and hydrofluorocarbons were measured to verify the accuracy of the apparatus, revealing a good consistency with the literature Totally 20 different compositions of the R23 + R32 system in the temperature range from 10700 K to 13700 K were experimentally measured, which showed a eutectic behavior The eutectic temperature is 10750 ± 05 K with the latent heat of fusion of 6713 J/g, and the mole fraction of R23 at the eutectic point is calculated to be 0641 by Tamman's plot method Moreover, the results for the solid – liquid equilibrium of the R23 + R32 system showed a good agreement with the prediction provided by the Schroder equation, with the deviation of eutectic temperature less than 1 K

Confirming NGC 6231 as the parent cluster of the runaway high-mass X-ray binary HD 153919/4U 1700-37 with Gaia DR2

Abstract: A significant fraction of the most massive stars move through space with a high velocity. One of the possible physical explanations is that a supernova in a compact binary system results in a high recoil velocity of the system. If the system remains bound, it can be subsequently observed as a spectroscopic binary (SB1), a high-mass X-ray binary, a compact binary, and finally a gravitational-wave event. If such a system is traced back to its parent cluster, binary evolution models can be tested in great detail. The Gaia proper motions and parallaxes are used to demonstrate that the high-mass X-ray binary HD153919/4U 1700-37 originates from NGC6231, the nucleus of the OB association Sco OB1. The O supergiant and its compact companion, of which the physical nature (a neutron star or a black hole) is unknown, move with a space velocity of 63 km/s with respect to NGC6231. The kinematical age of the system is 2.2 Myr. The parallaxes and accurate proper motions in Gaia DR2 were used to perform a membership analysis of NGC 6231. The distance to NGC6231 is 1.63 kpc. Isochrone fitting results in an age of 4.7 Myr. With the identification of NGC6231 as the parent cluster, the upper limit on the age of the progenitor of 4U1700-37 at the moment of the supernova explosion is 3.0 Myr. With these constraints, the evolutionary history of the system can be reconstructed with an initial mass of the progenitor of the compact object >60 Msun. Given its current high space velocity and the derived evolutionary history, the compact object in the system is more likely to have received a large natal kick, which suggests that it is more likely a neutron star than a black hole. HD153919/4U1700-37 might be a prototype in the Milky Way for the progenitor of gravitational wave events such as GW190412

Effects of Temperature and Pressure on Interfacial Tensions of Fluid Mixtures. I. CO2/n-Pentane Binary

Abstract: The effects of temperature and pressure on interfacial tension (IFT) of a CO2/n-pentane binary system were investigated using the pendant drop method. To ensure the accuracy and reproducibility of ...

Determination of the solubility and thermodynamic properties of albendazole in a binary solvent of ethanol and water

Abstract: The solubility of albendazole (ABZ) in a binary system of ethanol and water were determined experimentally by using a static analytical method within the temperature range (288.95 to 317.25) K unde...

The formation of binary star clusters in the Milky Way and Large Magellanic Cloud

Abstract: Recent observations of young embedded clumpy clusters and statistical identifications of binary star clusters have provided new insights into the formation process and subsequent dynamical evolution of star clusters. The early dynamical evolution of clumpy stellar structures provides the conditions for the origin of binary star clusters. Here, we carry out $N$-body simulations in order to investigate the formation of binary star clusters in the Milky Way and in the Large Magellanic Cloud (LMC). We find that binary star clusters can form from stellar aggregates with a variety of initial conditions. For a given initial virial ratio, a higher degree of initial substructure results in a higher fraction of binary star clusters. The number of binary star clusters decreases over time due to merging or dissolution of the binary system. Typically, $\sim 45\%$ of the aggregates evolve into binary/multiple clusters within $t=20$~Myr in the Milky Way environment, while merely $\sim30\%$ survives beyond $t=50$~Myr, with separations $\lesssim 50$~pc. On the other hand, in the LMC, $\sim 90\%$ of the binary/multiple clusters survive beyond $t=20$~Myr and the fraction decreases to $\sim 80\%$ at $t=50$~Myr, with separations $\lesssim 35~$pc. Multiple clusters are also rapidly formed for highly-substructured and expanding clusters. The additional components tend to detach and the remaining binary star cluster merges. The merging process can produce fast rotating star clusters with mostly flat rotation curves that speed up in the outskirts.