Browsing by Author "Baird, James K."

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Estimation of the Moments of the Residence Time and First Passage Time from Experimentally Measurable Permeation Parameters via a New Formulation of the Transmission Matrix
(2014-08-01)
Chen, Jenn-Shing
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Yeh, Kwei-Tin
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Chang, Wen-Yih
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Baird, James K.
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應用化學系
Siegel\'s analysis on membrane transport in the Laplace domain [J. Phys. Chem. 95 (1991) 2556] in terms of transmission matrix, T(s), has been extended to a more useful formulation. This is achieved by combining uses of the matrix transport equations appropriate for void initial condition, or for saturated equilibrium, or of Dirac delta functional type and the theorem det[T(s)]=1. This formulation enables us to expand T(s) in power series of the Laplace variable, s, with the expansion coefficients as the algebraic functions of the experimentally measurable transport parameters. Utility of the formulation is illustrated in the estimation of the experimentally inaccessible time moments for the first passage or residence times. It was also applied to the percutaneous drug delivery to obtain from the experimental data. The higher moments of the time lag or time lead using a graphic method.
Toward a Better Determination of Infrared Molar Absorptivities and Dimer Formation Constants in Self-association Through Hydrogen Bonding: 3-Ethyl-2-methyl-3-pentanol in Tetrachloroethylene as an Example
(2017-10-01)
Chen, Jenn-Shing
;
Yeh, Kwei-Tin
;
Kao, Dah-Yu
;
Baird, James K.
;
應用化學系
The monomer-dimer self-association of the dilute 3-ethyl-2-methyl-3-pentanol in tetrachloroethylene in the very dilute state was studied by infrared spectroscopy at several temperatures. The solute was deliberately chosen so that higher oligomers were suppressed by the steric hindrance arising from bulky groups on both sides of hydroxyl group. Two linear utility equations were derived to treat, respectively, the integrated absorbance of the monomer band, A(m), and of the dimer band, A(d), as functions of the initially prepared solute concentration, [B](0). The respective molar absorptivities were obtained by fitting these equations to the data. Unlike previous methods, the dimerization constant (K) can be obtained from either A(m) or A(d). Any discrepancy between these two values of K serves as a measure of the quality of the data. The values of K at different temperatures were employed to calculate the standard enthalpy and entropy of dimerization by using a van't Hoff plot. The dimer is predominantly in the cyclic form where both hydroxyl protons are hydrogen-bonded. This is inferred from the following observations: (1) the spectrum displays only two bands between 3300 and 3750 cm(-1); (2) the constancy of A(d)/A(m)(2) as a function of [B](0); and (3) the linearity of both plots [B](0)/A(m) vs. A(m), and [B](0)/A(d) vs. A(d)(2).