ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 04 Apr 2020 22:38:09 GMT2020-04-04T22:38:09Z50221- Multidensity integral equation theory for a sticky hard sphere-hard sphere heteronuclear dimer fluid: Thermodynamic and structural propertieshttps://scholarbank.nus.edu.sg/handle/10635/92152Title: Multidensity integral equation theory for a sticky hard sphere-hard sphere heteronuclear dimer fluid: Thermodynamic and structural properties
Authors: Wu, N.; Chiew, Y.C.
Abstract: A study of the structural and thermodynamic properties of a sticky hard sphere heteronuclear dimer fluid was performed using the multidensity Ornstein-Zernike integral equation theory. In this formalism, the modeling of a monodisperse system of the heteronuclear dimer was done as an equal molar binary mixture of associating sticky hard sphere and hard sphere particles in the complete association limit. A analytical solution to the model was obtained within the polymer Percus-Yevick and Percus-Yevick approximations. Critical density, critical temperature and phase coexistence of the fluid was also obtained.
Mon, 08 Oct 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/921522001-10-08T00:00:00Z
- Perturbed Lennard-Jones chain equation of state for polymer liquidshttps://scholarbank.nus.edu.sg/handle/10635/92221Title: Perturbed Lennard-Jones chain equation of state for polymer liquids
Authors: Chiew, Y.C.; Ting, S.K.H.; Leong, K.K.
Abstract: The perturbed Lennard-Jones chain (PLJC) equation of state is formulated based on the first-order variational perturbation theory. The model consists of three parameters, namely, number of segments per chain molecule, m, segment size, σ, and segment energy, ε/k. Given the molecular weight, the PLJC equation was used to quantify the pressure-specific volume-temperature properties of a large number of polymer liquids. Very good agreement was found between the predicted and experimentally measured specific volumes. The accuracy of the PLJC equation of state compares favorably with other polymer equations of state. We further proposed a modification to the PLJC equation to include the molecular weight as a parameter in the equation of state and hence, rendering the modified equation of state, itself molecular weight-independent. This modified perturbed Lennard-Jones chain (mPLJC) model was found to represent experimentally measured data very well.
Tue, 01 Feb 2000 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/922212000-02-01T00:00:00Z
- Application of the perturbed Lennard-Jones chain equation of state to solute solubility in supercritical carbon dioxidehttps://scholarbank.nus.edu.sg/handle/10635/63505Title: Application of the perturbed Lennard-Jones chain equation of state to solute solubility in supercritical carbon dioxide
Authors: Huang, Z.; Kawi, S.; Chiew, Y.C.
Abstract: The perturbed Lennard-Jones chain (PLJC) equation of state is a thermodynamic model based on the perturbation theory of liquid state. This equation has been shown in the past to be a successful model for phase equilibria calculations of binary and ternary fluid mixtures and polymer solutions. In this work, we employed for the first time the PLJC equation to model the solubility of 39 solids in supercritical carbon dioxide. It was shown that the model achieves good correlation with three temperature independent parameters. A comparison of the PLJC with the commonly used Peng-Robinson equation reveals the PLJC equation gives better correlation to the solubility data than the Peng-Robinson model that utilizes temperature dependent parameters. © 2003 Elsevier B.V. All rights reserved.
Sun, 15 Feb 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/635052004-02-15T00:00:00Z
- Thermodynamic and structural properties of Yukawa hard chainshttps://scholarbank.nus.edu.sg/handle/10635/92449Title: Thermodynamic and structural properties of Yukawa hard chains
Authors: Wang, X.-Y.; Chiew, Y.C.
Abstract: Thermodynamic properties and intra- and intermolecular correlation functions of Yukawa hard chains were studied. A first order perturbation theory using hard-sphere chain fluid as reference was used to calculate the compressibility factor of Yukawa chain fluids. Results of Monte Carlo simulations were compared with those of the theory and Statistical Associating Fluid Theory-Variable Range model. The local structure of Yukawa hard chains was found to be affected by the range parameter of Yukawa potential.
Sat, 01 Sep 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/924492001-09-01T00:00:00Z
- Solubility of cholesterol and its esters in supercritical carbon dioxide with and without cosolventshttps://scholarbank.nus.edu.sg/handle/10635/90179Title: Solubility of cholesterol and its esters in supercritical carbon dioxide with and without cosolvents
Authors: Huang, Z.; Kawi, S.; Chiew, Y.C.
Abstract: The solubilities of cholesterol and its esters - cholesteryl acetate, cholesteryl butyrate and cholesteryl benzoate - in supercritical carbon dioxide were measured using a dynamic flow method. We also examined the effect of a polar cosolvent, namely methanol or acetone, on the solubility of these compounds in supercritical carbon dioxide and found that the solubilities of these compounds are enhanced several fold depending on the pressure of the system. The solubility data were correlated using the Peng-Robinson equation of state (PR EOS) and density-based correlations. Model parameters for the systems studied are obtained through data regression. © 2003 Elsevier B.V. All rights reserved.
Tue, 01 Jun 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/901792004-06-01T00:00:00Z
- A perturbed Lennard-Jones chain equation of state for polymer mixtures: Applications to vapor-liquid and liquid-liquid equilibriahttps://scholarbank.nus.edu.sg/handle/10635/91854Title: A perturbed Lennard-Jones chain equation of state for polymer mixtures: Applications to vapor-liquid and liquid-liquid equilibria
Authors: Lee, Y.P.; Rangaiah, G.P.; Chiew, Y.C.
Abstract: The perturbed Lennard-Jones chain (PLJC) equation of state (EOS) is extended to polymer mixtures. This equation utilizes the hard-sphere chain mixture as the reference system, while the perturbation term is derived based on the first-order variational theory. Binary vapor-liquid equilibrium (VLE) data of a wide range of polymer mixtures are well described by this model through the use of one binary parameter kij. We also show that the PLJC model is able to predict liquid-liquid equilibrium of polymer-solvent systems satisfactorily by introducing an empirical parameter that adjusts the degree of perturbation in the model. All phase equilibrium calculations in this study were performed rigorously by global minimization of Gibbs free energy using a genetic algorithm. © 2001 Elsevier Science B.V. All rights reserved.
Mon, 15 Oct 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/918542001-10-15T00:00:00Z
- Thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluidhttps://scholarbank.nus.edu.sg/handle/10635/92448Title: Thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluid
Authors: Wu, N.; Feng, S.S.; Chiew, Y.C.
Abstract: The multidensity Ornstein-Zernike integral equation theory was applied to study the thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluid. The sticky strength of each species was obtained as a function of density and temperature. Static structure factors of homonuclear dimer at different temperatures were calculated. The system exhibited a first-order phase change and Van der Waals loop.
Sun, 01 Sep 2002 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/924482002-09-01T00:00:00Z
- Monte Carlo simulations of conformations of short chains near a cylindrical rodhttps://scholarbank.nus.edu.sg/handle/10635/92148Title: Monte Carlo simulations of conformations of short chains near a cylindrical rod
Authors: Chen, S.B.; Wang, X.-Y.; Chiew, Y.C.
Abstract: An off-lattice Monte Carlo simulation method was employed to study the conformations of short chains near a long rigid rod. The chains were observed to be elongated when located sufficiently near the rod surface, and show a very interesting transition in anisotropy.
Tue, 01 Jul 2003 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/921482003-07-01T00:00:00Z
- Second virial coefficients of Lennard-Jones chainshttps://scholarbank.nus.edu.sg/handle/10635/92321Title: Second virial coefficients of Lennard-Jones chains
Authors: Chiew, Y.C.; Sabesan, V.
Abstract: The second virial coefficients B2 of Lennard-Jones chain fluids were calculated through Monte Carlo integration as a function of chain length m (up to 48 segments) and temperature. We found that at a fixed temperature the second virial coefficient decreases with chain length. At low temperatures, the virial coefficient changes sign from positive to negative as m increases. The simulation data also provide an estimate for the theta temperature TΘ at which the attractive and repulsive interactions cancel each other for dilute solutions. It is found that the theta temperature TΘ for Lennard-Jones chains with m > 32 is 4.65 independent of chain length m. A comparison of simulated values of B2 with those evaluated from two different perturbation theories for chain fluid shows that these approximate theories underestimate the second virial coefficients of Lennard-Jones chains.
Fri, 05 Feb 1999 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/923211999-02-05T00:00:00Z
- Mixing rules for binary Lennard-Jones chains: Theory and Monte Carlo simulationhttps://scholarbank.nus.edu.sg/handle/10635/92127Title: Mixing rules for binary Lennard-Jones chains: Theory and Monte Carlo simulation
Authors: Von Solms, N.; Koo, K.Y.; Chiew, Y.C.
Abstract: Theoretically-based van der Waals one-fluid (vdW1) mixing rules are derived for Lennard-Jones (LJ) chain mixtures. The rules provide equivalent one-fluid segment parameters for LJ size (σ) and energy (ε) parameter as well as chain length (m) based on the parameters of the individual mixture components and the component mole fractions. The mixing rules are tested by performing Monte Carlo simulations of eight different binary mixtures and the equivalent vdW1 pure fluid, each at three densities. The simulations test the effects of changing LJ size parameter, LJ energy parameter and chain length individually and together. The effects of mole fraction and density are also examined. The mixing rules are tested for accuracy in predicting compressibility factors and radial distribution functions. It is found that the vdW1 rules provide excellent agreement when size and energy parameter are varied. Good agreement is found for mixtures with different chain lengths. The discrepancy is worst at very high densities when all component parameters are varied simultaneously. Copyright © 2001 .
Sun, 15 Apr 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/921272001-04-15T00:00:00Z
- Dynamics of adsorption and desorption of proteins at an air/water interfacehttps://scholarbank.nus.edu.sg/handle/10635/66536Title: Dynamics of adsorption and desorption of proteins at an air/water interface
Authors: Jiang, Q.; Chiew, Y.C.
Abstract: Adsorption and desorption dynamics of lysozyme and β-casein at the air/water interface were investigated through stress relaxation experiments. The resulting surface tension changes due to a step-type surface area disturbance, as a function of time, were measured through a capillary wave probe. The adsorption data, obtained after a surface area expansion, can be well fitted to a diffusion-controlled adsorption model. However, desorption relaxation following a surface compression is much slower and cannot be modeled by the diffusion theory. Characteristic diffusion frequency and high-frequency dilational elasticity for protein layers were also obtained and found to be consistent with data reported in the literature. Copyright © 2001 Elsevier Science B.V.
Mon, 01 Jan 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/665362001-01-01T00:00:00Z
- Adsorption of single component and binary mixtures of protein and surfactants at the oil-water interfacehttps://scholarbank.nus.edu.sg/handle/10635/66432Title: Adsorption of single component and binary mixtures of protein and surfactants at the oil-water interface
Authors: Sudah, O.S.; Chen, G.; Chiew, Y.C.
Abstract: The dynamic interfacial tensions of non-ionic Triton X-100 surfactants, chicken-egg-white lysozyme proteins, and binary mixtures of Triton X-100-lysozyme at the dodecane-water interface were measured using a capillary wave technique. Consistent with results reported in the literature, the adsorption of Triton X-100 was found to be diffusion-controlled. The adsorption of lysozyme is well represented by a series of two first-order relaxation processes, which, respectively, had been identified in the literature as related to the adsorption/penetration of protein onto the interface and rearrangement/unfolding to its equilibrium in the interface. Our data show that the second process is the slower of the two. For Triton X-100-lysozyme binary mixtures, we found that the presence of nonionic Triton surfactants has little or no effect on the first process. In contrast, the Triton surfactants play a significant role in impeding the rearrangement/unfolding of the protein molecules in the interface. Copyright (C) 1999 Elsevier Science B.V.
Sat, 01 May 1999 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/664321999-05-01T00:00:00Z
- Connectedness-in-probability and continuum percolation of adhesive hard spheres: Integral equation theoryhttps://scholarbank.nus.edu.sg/handle/10635/66504Title: Connectedness-in-probability and continuum percolation of adhesive hard spheres: Integral equation theory
Authors: Chiew, Y.C.
Abstract: Integral equation theory was employed to study continuum percolation and clustering of adhesive hard spheres based on a "connectedness-in-probability" criterion. This differs from earlier studies in that an "all-or-nothing" direct connectivity criterion was used. The connectivity probability may be regarded as a "hopping probability" that describes excitation that passes from one particle to another in complex fluids and dispersions. The connectivity Ornstein-Zernike integral equation was solved for analytically in the Percus-Yevick approximation. Percolation transitions and mean size of particle clusters were obtained as a function of connectivity probability, stickiness parameter, and particle density. It was shown that the pair-connectedness function follows a delay-differential equation which yields analytical expressions in the Percus-Yevick theory. © 1999 American Institute of Physics.
Tue, 01 Jun 1999 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/665041999-06-01T00:00:00Z
- Perturbed Lennard-Jones chain equation of state for polymer liquidshttps://scholarbank.nus.edu.sg/handle/10635/66738Title: Perturbed Lennard-Jones chain equation of state for polymer liquids
Authors: Chiew, Y.C.; Ting, S.K.H.; Leong, K.K.
Abstract: The perturbed Lennard-Jones chain (PLJC) equation of state is formulated based on the first-order variational perturbation theory. The model consists of three parameters, namely, number of segments per chain molecule, m, segment size, σ, and segment energy, ε/k. Given the molecular weight, the PLJC equation was used to quantify the pressure-specific volume-temperature properties of a large number of polymer liquids. Very good agreement was found between the predicted and experimentally measured specific volumes. The accuracy of the PLJC equation of state compares favorably with other polymer equations of state. We further proposed a modification to the PLJC equation to include the molecular weight as a parameter in the equation of state and hence, rendering the modified equation of state, itself molecular weight-independent. This modified perturbed Lennard-Jones chain (mPLJC) model was found to represent experimentally measured data very well.
Tue, 01 Feb 2000 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/667382000-02-01T00:00:00Z
- Thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluidhttps://scholarbank.nus.edu.sg/handle/10635/66886Title: Thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluid
Authors: Wu, N.; Feng, S.S.; Chiew, Y.C.
Abstract: The multidensity Ornstein-Zernike integral equation theory was applied to study the thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluid. The sticky strength of each species was obtained as a function of density and temperature. Static structure factors of homonuclear dimer at different temperatures were calculated. The system exhibited a first-order phase change and Van der Waals loop.
Sun, 01 Sep 2002 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/668862002-09-01T00:00:00Z
- Thermodynamic and structural properties of Yukawa hard chainshttps://scholarbank.nus.edu.sg/handle/10635/66887Title: Thermodynamic and structural properties of Yukawa hard chains
Authors: Wang, X.-Y.; Chiew, Y.C.
Abstract: Thermodynamic properties and intra- and intermolecular correlation functions of Yukawa hard chains were studied. A first order perturbation theory using hard-sphere chain fluid as reference was used to calculate the compressibility factor of Yukawa chain fluids. Results of Monte Carlo simulations were compared with those of the theory and Statistical Associating Fluid Theory-Variable Range model. The local structure of Yukawa hard chains was found to be affected by the range parameter of Yukawa potential.
Sat, 01 Sep 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/668872001-09-01T00:00:00Z
- Mixing rules for binary Lennard-Jones chains: Theory and Monte Carlo simulationhttps://scholarbank.nus.edu.sg/handle/10635/66670Title: Mixing rules for binary Lennard-Jones chains: Theory and Monte Carlo simulation
Authors: Von Solms, N.; Koo, K.Y.; Chiew, Y.C.
Abstract: Theoretically-based van der Waals one-fluid (vdW1) mixing rules are derived for Lennard-Jones (LJ) chain mixtures. The rules provide equivalent one-fluid segment parameters for LJ size (σ) and energy (ε) parameter as well as chain length (m) based on the parameters of the individual mixture components and the component mole fractions. The mixing rules are tested by performing Monte Carlo simulations of eight different binary mixtures and the equivalent vdW1 pure fluid, each at three densities. The simulations test the effects of changing LJ size parameter, LJ energy parameter and chain length individually and together. The effects of mole fraction and density are also examined. The mixing rules are tested for accuracy in predicting compressibility factors and radial distribution functions. It is found that the vdW1 rules provide excellent agreement when size and energy parameter are varied. Good agreement is found for mixtures with different chain lengths. The discrepancy is worst at very high densities when all component parameters are varied simultaneously. Copyright © 2001 .
Sun, 15 Apr 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/666702001-04-15T00:00:00Z
- Multidensity integral equation theory for a sticky hard sphere-hard sphere heteronuclear dimer fluid: Thermodynamic and structural propertieshttps://scholarbank.nus.edu.sg/handle/10635/66691Title: Multidensity integral equation theory for a sticky hard sphere-hard sphere heteronuclear dimer fluid: Thermodynamic and structural properties
Authors: Wu, N.; Chiew, Y.C.
Abstract: A study of the structural and thermodynamic properties of a sticky hard sphere heteronuclear dimer fluid was performed using the multidensity Ornstein-Zernike integral equation theory. In this formalism, the modeling of a monodisperse system of the heteronuclear dimer was done as an equal molar binary mixture of associating sticky hard sphere and hard sphere particles in the complete association limit. A analytical solution to the model was obtained within the polymer Percus-Yevick and Percus-Yevick approximations. Critical density, critical temperature and phase coexistence of the fluid was also obtained.
Mon, 08 Oct 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/666912001-10-08T00:00:00Z
- Monte Carlo simulations of conformations of short chains near a cylindrical rodhttps://scholarbank.nus.edu.sg/handle/10635/66688Title: Monte Carlo simulations of conformations of short chains near a cylindrical rod
Authors: Chen, S.B.; Wang, X.-Y.; Chiew, Y.C.
Abstract: An off-lattice Monte Carlo simulation method was employed to study the conformations of short chains near a long rigid rod. The chains were observed to be elongated when located sufficiently near the rod surface, and show a very interesting transition in anisotropy.
Tue, 01 Jul 2003 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/666882003-07-01T00:00:00Z
- Solubility of cholesterol and its esters in supercritical carbon dioxide with and without cosolventshttps://scholarbank.nus.edu.sg/handle/10635/64606Title: Solubility of cholesterol and its esters in supercritical carbon dioxide with and without cosolvents
Authors: Huang, Z.; Kawi, S.; Chiew, Y.C.
Abstract: The solubilities of cholesterol and its esters - cholesteryl acetate, cholesteryl butyrate and cholesteryl benzoate - in supercritical carbon dioxide were measured using a dynamic flow method. We also examined the effect of a polar cosolvent, namely methanol or acetone, on the solubility of these compounds in supercritical carbon dioxide and found that the solubilities of these compounds are enhanced several fold depending on the pressure of the system. The solubility data were correlated using the Peng-Robinson equation of state (PR EOS) and density-based correlations. Model parameters for the systems studied are obtained through data regression. © 2003 Elsevier B.V. All rights reserved.
Tue, 01 Jun 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/646062004-06-01T00:00:00Z
- A model for polyelectrolyteshttps://scholarbank.nus.edu.sg/handle/10635/54399Title: A model for polyelectrolytes
Authors: Von Solms, N.; Chiew, Y.C.
Abstract: We have solved a polymerizing version of the mean spherical approximation (MSA) tor polyelectrolytes. The polyelectrolytes are modeled as tangentially bonded hard-sphere segments interacting via the Coulombic potential in a continuous medium with dielectric constant. Analytical solutions lor thermodynamic properties and radial distribution functions at contact are obtained for some specific systems (negatively charged chains and counterions) studied in the literature via computer simulations, with which good agreement is found for the osmotic pressure.
Sat, 01 Jul 2000 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/543992000-07-01T00:00:00Z
- A molecular-based model for normal fluid mixtures: Perturbed Lennard- Jones chain equation of statehttps://scholarbank.nus.edu.sg/handle/10635/54438Title: A molecular-based model for normal fluid mixtures: Perturbed Lennard- Jones chain equation of state
Authors: Lee, Y.P.; Chiew, Y.C.; Rangaiah, G.P.
Abstract: The perturbed Lennard-Jones chain (PLJC) equation of state, previously used for pure fluids, is extended to normal fluid mixtures. The PLJC equation utilizes the hard-sphere chain mixture as the reference system, while the perturbation term is derived based on the first-order variational theory. Binary vapor-liquid equilibrium data of a wide range of fluids were well described by this model through the use of one binary parameter k(ij). We showed that the PLJC equation of state was able to predict vapor-liquid equilibrium fairly accurately using binary data. Also, the PLJC equation is able to model retrograde condensation and liquid-liquid-vapor three-phase equilibrium of ternary mixtures without the need to reevaluate binary parameters. Theoretical phase equilibrium compositions were determined through an isothermal isobaric flash calculation based on global minimization of the Gibbs free energy using a genetic algorithm.
Sat, 01 Jan 2000 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/544382000-01-01T00:00:00Z