Chemistry

1308 Submissions

[2] viXra:1308.0154 [pdf] submitted on 2013-08-31 12:46:35

Comment on "Representation and Prediction of Molecular Diffusivity of Nonelectrolyte Organic Compounds in Water at Infinite Dilution Using the Artificial Neural Network-Group Contribution Method [Gharagheizi et al., J. Chem. Eng. Data 2011, 56, 1741-1750]

Authors: Sierra Rayne
Comments: 1 Page.

In their article, Gharagheizi et al. [J. Chem. Eng. Data 2011, 56, 1741-1750] claim to develop a model to predict the molecular diffusivity of "nonelectrolyte organic compounds" in water using an artificial neural network-group contribution method. Many of these compounds have ionizable functionalities with pKa values that result in either substantial or effectively complete ionization in water (making them electrolytes, in contrast to the claims of Gharagheizi et al.). Consequently, the model developed and applied by Gharagheizi et al. does not computationally model the actual speciation(s) of each compound expected to be present under the experimental conditions for which the underlying data has been obtained and erroneously classifies many organic compounds as non-electrolytes.
Category: Chemistry

[1] viXra:1308.0153 [pdf] submitted on 2013-08-31 13:00:18

Comment on "Comparison of New and Existing Threshold Methods for Evaluating Sulfur Compounds in Different Base Wines"

Authors: Sierra Rayne
Comments: 1 Page.

In their article (Cliff et al., J. Sens. Stud., 2011, 26, 184-196), the authors plot the log mean aroma threshold concentrations for three sulfur aroma compound analytes on the y-axis against the qualitative descriptors of the wine (i.e., "model," "neutral," and "fruity") on the x-axis, and proceed to fit three log-linear regression models through the sets of data. The statistical validity of this exercise seems problematic (particularly with only three datapoints, and four significant figures in the resulting quoted regression constants), and the reason behind this choice of data analysis is unclear. Some type of statistical test (e.g., ANOVA) designed to investigate relative trend differences between categorical variables would perhaps be more appropriate, especially when such nebulous categorical descriptors as "neutral" and "fruity" are being employed along the x-axis and ordered in an arbitrary manner.
Category: Chemistry