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UNT College of Arts and Sciences
Experimental Artifacts and Determination of Accurate Py Values
Date: 1986
Creator: Street, Kenneth W. & Acree, William E. (William Eugene)
Description: This article discusses experimental artifacts and determination of accurate Py values. Abstract: Recently the Py solvent scale has been introduced and a large body of data has been generated using fluorescence measurements. Numerous problems exist in the correct determination of these values, including instrumental and chemical artifacts. Among the instrumental problems associated with correct Py assignments are slit width effects, inner filtering and efficiencies associated with double-pass vs. single-pass cell compartment designs. These instrumental problems, together with chemical artifacts related to adequate blank correction and temperature control, were investigated in the work reported in this paper.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152446/
Sume calculabile prin serii de puteri
Date: 2004
Creator: Anghel, Nicolae
Description: This paper investigates an efficient way of evaluating sums and series, based on a result of Abel applied to associated power series.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152458/
Generalizarea problemei 0:59
Date: 1980
Creator: Anghel, Nicolae
Description: This note extends a certain combinatorics problem of I. Tomescu.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152440/
O generalizare a problemei piesei de 5 lei a lui Ţiţeica
Date: November 2012
Creator: Anghel, Nicolae
Description: The '5 lei coin' problem of Titeica is generalized to circles of arbitrary radii.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152461/
Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds. Sublimation, Vaporization and Fusion Enthalpies From 1880 to 2010
Date: October 4, 2010
Creator: Acree, William E. (William Eugene) & Chickos, James S.
Description: This article discusses phase transition enthalpy measurements of organic and organometallic compounds. A compendium of phase change enthalpies published within the period 1880-2010 is reported. Phase change enthalpies including fusion, vaporization, and sublimation are included for organic, organometallic, and a few inorganic compounds. This compendium is a combination of three previous series focusing on phase change enthalpies updated to 2009. Sufficient data are presently available for some compounds to permit thermodynamic cycles to be constructed, an important manner of evaluating the reliability of the measurements. Temperature adjustments of phase change enthalpies from the temperature of measurement to the standard reference temperature, T = 298.15 K, are briefly discussed and a protocol for doing so is illustrated.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152426/
Prediction of Partition Coeffecients and Permeability of Drug Molecules in Biological Systems with Abraham Model Solute Descriptors Derived from Measured Solubilities and Water-to-Organic Solvent Partition Coefficients
Date: February 10, 2012
Creator: Acree, William E. (William Eugene); Grubbs, Laura M. & Abraham, M. H. (Michael H.)
Description: This book chapter discusses the prediction of partition coefficients and permeability of drug molecules in biological systems with Abraham model solute descriptors derived from measured solubilities and water-to-organic solvent partition coefficients.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152436/
Chemical Toxicity Correlations for Several Fish Species Based on the Abraham Solvation Parameter Model
Date: September 1, 2005
Creator: Hoover, Kaci R.; Acree, William E. (William Eugene) & Abraham, M. H. (Michael H.)
Description: This article discusses chemical toxicity correlations for several fish species based on the Abraham solvation parameter model. Abstract: The Abraham solvation parameter model is used to construct mathematical correlations for describing the nonspecific aquatic toxicity of organic compounds to the fathead minnow, guppy, bluegill, goldfish, golden orfe, and high-eyes medaka. The derived mathematical correlations describe the observed published toxicity data to within an overall average standard deviation of approximately 0.28 log units. In the case of ester solutes, the descriptions were improved by introducing an indicator variable into the basic model. Derived correlations can be used to estimate aquatic toxicities of organic chemicals to the six fish species studied and to help in identifying compounds whose toxic mode of action might involve chemical specific reactivity, rather than nonpolar or polar narcosis. A principle component analysis of the correlation equations shows that the water-octanol system is a poor model for nonspecific aquatic toxicity but that the water-isobutanol and water-pentanol systems are much better models.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152447/
Solubility of Pyrene in Binary Solvent Mixtures Containing Cyclohexane
Date: January 1987
Creator: Judy, Cheryl L.; Pontikos, Nicholas M. & Acree, William E. (William Eugene)
Description: This article discusses solubility of pyrene in binary solvent mixtures containing cyclohexane. Abstract: Solubilities are reported for pyrene at 26.0 °C in binary mixtures of cyclohexane with n-hexane, n-heptane, n-octane, isooctane, and cyclooctane. The results of these measurements are compared to the predictions of equations developed previously for solubility in systems of nonspecific interactions. The nearly ideal binary solvent (NIBS) model predicts these solubilities with a maximum deviation of 4.8%, using as input data the solubility of pyrene in each pure solvent. The NIBS model correctly predicts a small maxima for the mole fraction solubility of pyrene in cyclohexane + n-heptane mixtures.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152448/
Solubility of Pyrene in Binary Solvent Mixtures Containing Dibutyl Ether
Date: January 1989
Creator: Wallach, Jordana R.; Tucker, Sheryl A.; Oswalt, Bridget M.; Murral, Debra J. & Acree, William E. (William Eugene)
Description: This article discusses the solubility of pyrene in binary solvent mixtures containing dibutyl ether. Experimental solubilities are reported for pyrene in binary solvent mixtures containing dibutyl ether with n-hexane, cyclohexane, n-heptane, methylcyclohexane, n-octane, isooctane, and tert-butylcyclohexane at 26 °C. Results of these measurements, combined with estimates for the excess Gibbs free energies of the binary solvents, are used to test predictive expressions derived from the nearly ideal binary solvent (NIBS) model. Expressions based on a volume fraction average of solute properties in the two pure solvents predict pyrene solubilities to within a maximum deviation of 10% and an overall average deviation of 3.2%.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152453/
Solubility of Phenylacetic Acid in Binary Solvent Mixtures
Date: January 1985
Creator: Acree, William E. (William Eugene)
Description: This article discusses the solubility of phenylacetic acid in binary solvent mixtures. Abstract: Solubilities are reported for phenylacetic acid at 25.0 °C in binary mixtures of carbon tetrachloride with cyclohexane, n-heptane, n-octane, or isooctane and mixtures of cyclohexane with n-heptane or isooctane. The results are compared to the predictions of equations developed previously for solubility in systems of purely nonspecific interactions, with phenylacetic acid considered as either monomeric or dimeric molecules in solution. The dimer model provided the more accurate predictions and described the 15-fold range of solubilities in the carbon tetrachloride + isooctane system to within a maximum deviation of 15%.
Contributing Partner: UNT College of Arts and Sciences
Permallink:digital.library.unt.edu/ark:/67531/metadc152445/