Publications

1991
K. E. Oshea, Kirmse, K. M., Fox, M. A., and Johnston, K. P., “POLAR AND HYDROGEN-BONDING INTERACTIONS IN SUPERCRITICAL FLUIDS - EFFECTS ON THE TAUTOMERIC EQUILIBRIUM OF 4-(PHENYLAZO)-1-NAPHTHOL,” Journal of Physical Chemistry, vol. 95, pp. 7863-7867, 1991. Publisher's VersionAbstract
The azo-hydrazone tautomeric equilibrium of 4-(phenylazo)-1-naphthol is compared in various liquid and supercritical fluid solvents. The less polar azo tautomer is dominant in the dilute gas phase, compressed ethane, and liquid alkanes. In liquid and supercritical CO2, the equilibrium shifts toward the more polar hydrazone, to yield similar amounts of the two tautomers. This shift is attributed to the Lewis acidity and large quadrupole moment of CO2. The dominance of the hydrazone tautomer in fluoroform (> 90%) can be attributed to that solvent’s large dipole moment and ability to act as a strong electron acceptor (hydrogen bond donor). Since acid-base interactions are prevalent at the lowest pressure studied (1000 psia), changes in the equilibrium constant as a function of pressure have been assigned primarily to increases in the nonspecific polar interactions. The large differences in the polarities, acidities, and basicities of these fluids, despite their similar polarizabilities per volume, are of interest for manipulating chemical processes and for practical applications of supercritical fluid science and technology.
J. F. Bard, “Some Properties of the Bilevel Programming Problem,” J. Optimization Theory and Applications, vol. 68, pp. 371–378, 1991.
R. B. Machemehl and Karachepone, J., “Texas Department of Transportation Final Transportation Planning Division,” 1991.Abstract
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R. B. Machemehl and Acampora, M., “Texas model validation for left-turn phasing alternatives,” 1991.Abstract
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R. B. Machemehl and Acampora, M., “TEXAS MODEL VALIDATION FOR LEFT-TURN PHASING ALTERNATIVES. FINAL REPORT”. 1991.Abstract
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D. G. Peck and Johnston, K. P., “THEORY OF THE PRESSURE EFFECT ON THE CURVATURE AND PHASE-BEHAVIOR OF AOT PROPANE BRINE WATER-IN-OIL MICROEMULSIONS,” Journal of Physical Chemistry, vol. 95, pp. 9549-9556, 1991. Publisher's VersionAbstract
Pressure effects on both the curvature and phase behavior of water-in-oil microemulsions (swollen reverse micelles) are predicted with a unified classical and molecular thermodynamic theory developed by Peck et al. (this issue). The theory is used to identify quantitatively the roles of the intramicellar interfacial interactions and micelle-micelle interactions. A supplementary molecular model is used to calculate the strength of attractive intermicellar interactions over a wide range of conditions, based on previous small-angle neutron-scattering data. An important distinction is made between systems with a small water-to-oil ratio and those where the water-to-oil ratio is much larger, on the order of unity. In the latter the micelle radius is controlled primarily by intramicellar interfacial interactions, specifically the enthalpic propane-surfactant tail interactions. For a small water-to-oil ratio, the micelle radius is limited by attractive micelle-micelle interactions. As pressure increases, the radius increases but eventually reaches a maximum governed by the intramicellar interfacial interactions. There is good agreement between the predictions and experiments over a wide range of water-to-oil ratios.
D. G. Peck, Schechter, R. S., and Johnston, K. P., “UNIFIED CLASSICAL AND MOLECULAR THERMODYNAMIC THEORY OF SPHERICAL WATER-IN-OIL MICROEMULSIONS,” Journal of Physical Chemistry, vol. 95, pp. 9541-9549, 1991. Publisher's VersionAbstract
A unified classical and molecular thermodynamic model is developed in order to predict the phase behavior and interfacial properties of spherical water-in-oil microemulsions. A modified Flory-Krigbaum theory is used to describe the interactions between the surfactant tails and solvent, while the ionic head-group interactions are treated with the Poisson-Boltzman equation. The interfacial tension and the bending moment of the interface are calculated explicitly. These values are incorporated into a classical thermodynamic framework that is forced to satisfy the Gibbs adsorption equation on the interface, guaranteeing thermodynamic consistency. Given a surfactant molecular architecture, the model predicts the size of microemulsion droplets as a function of the chain length of the alkane solvent. For bis(2-ethylhexyl) sodium sulfosuccinate (AOT) in the solvents propane through decane, the calculated trends agree with experiment and are explained mechanistically at the molecular level. The microemulsion radius increases for the solvents pentane through propane, an unusual behavior that is explained theoretically.
1990
C. T. Marcus, Machemehl, R. B., and Lee, C. E., “Auxiliary turning lanes at urban intersections,” 1990.Abstract
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C. T. Marcus, Machemehl, R. B., and Lee, C. E., “AUXILIARY TURNING LANES AT URBAN INTERSECTIONS. FINAL REPORT”. 1990.Abstract
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J. F. Bard and Moore, J. T., A Branch and Bound Algorithm for the Bilevel Programming Problem. SIAM Journal on Scientific and Statistical Computing 11(2) 281-292, 1990.
H. F. Morrison, Nichols, E. A., Torres-Verdín, C., Booker, J. R., and Constable, S. C., “A comparison of magnetotelluric inversion techniques on a mineral prospect in Nevada: (Expanded Abstract): Soc,” Society of Exploration Geophysicists 60th Annual International Meeting. Society of Exploration Geophysicists, San Francisco, CA, 1990.
H. F. Morrison, Nichols, E. A., Torres-Verdín, C., Booker, J. R., and Constable, S. C., “A comparison of magnetotelluric inversion techniques on a mineral prospect in Nevada: (Expanded Abstract): Soc,” Society of Exploration Geophysicists 60th Annual International Meeting. Society of Exploration Geophysicists, San Francisco, CA, 1990.
S. Modur, Machemehl, R. B., and Lee, C. E., Criteria for the Selection of a Left-turn Median Design. Center for Transportation Research, University of Texas at Austin, 1990.Abstract
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S. Modur, Machemehl, R. B., and Lee, C. E., “CRITERIA FOR THE SELECTION OF A LEFT-TURN MEDIAN DESIGN. FINAL REPORT”. 1990.Abstract
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T. A. Edmunds and Bard, J. F., A Decomposition Technique for Discrete Time Optimal Control Problems with an Application to Water Resources Management. Mathematical and Computer Modelling 13(1) 61-78, 1990.
M. A. Middleton, Schechter, R. S., and Johnston, K. P., “DIELECTRIC-PROPERTIES OF ANIONIC AND NONIONIC SURFACTANT MICROEMULSIONS,” Langmuir, vol. 6, pp. 920-928, 1990. Publisher's VersionAbstract
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J. T. Moore and Bard, J. F., The Mixed Integer Linear Bilevel Programming Problem. Operations Research 38(5), 1990, pp. 911–921.
K. P. Johnston and Shim, J. J., “MOLECULAR THERMODYNAMICS OF SORPTION OF SOLUTES INTO POLYMERS UNDER SUPERCRITICAL FLUID CONDITIONS,” Abstracts of Papers of the American Chemical Society, vol. 199, pp. 397-POLY, 1990. Publisher's VersionAbstract
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J. F. Bard and Moore, J. T., Production Planning with Variable Demand. Omega 18(1) 35-42, 1990.
C. Torres-Verdín and Bostick Jr, F. X., “Properties of EMAP in two-dimensional environments (Expanded Abstract),” Society of Exploration Geophysicists 60th Annual International Meeting. Society of Exploration Geophysicists, San Francisco, CA, 1990.

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