Erratum: Explanation of Variability and Removal of Confounding Factors from Data through Optimal Transport

Due to a production error, the version of this article published in the print edition of the January 2018 issue had the wrong graphics for Figures 4.1 (p. 176), 4.3 (p. 179), 4.4 (p. 180), and 5.2 (p. 192). The correct figures are provided below. These corrected figures have been incorporated into the online version of the article.     

Parametric signal fitting by gaussian peak adjustment: A new multivariate curve resolution method for non-bilinear voltammetric measurements

A new methodology based on the fitting of signals to parametric functions is proposed for the multivariate curve resolution (MCR) analysis of overlapping and peak-shaped voltammetric signals which progressively get broader or narrower and move along the potential axis, thus causing a dramatic loss of linearity. The method is based on the least squares fitting of gaussian functions at both sides of the peaks by using adjustable parameters for the peak height, position and symmetry. It consists of several home-made programs written in Matlab environment, which are freely available as supplementary material of the present work. The application to the systems Zn(II)–oxalate, and to the phytochelatin PC₅ in a wide pH range provides excellent results as compared to these of more conventional linear methods, which raises good expectations about future application to electrochemical and even non-electrochemical data.     

Rheological aspects of the rejuvenation of aged bitumen

Rheological techniques are used to investigate the rejuvenation of aged bitumen. The thermal transition associated with the collapse of the compact structure constituted by asphaltene is determined by Dynamic Mechanical Thermal Analysis. For aged bitumen, this transition shifts to a higher temperature but when rejuvenating agents are added, the transition returns to its original value. The “rutting factor,” G*/sin δ allows to define the maximum temperature the binder can reach without permanent deformation. The employed rejuvenating agents are suitable because permanent deformation is postponed. Viscosity results reveal that aged bitumen needs a high mixing temperature (>200°C) to behave like a fluid material able to wet, adhere, and envelop aggregates. The addition of rejuvenating agents considerably reduces mixing and compaction temperatures. The mixture of 80% aged bitumen—20% recycled motor oil, obtained exclusively from waste materials is an apt binder that can compete satisfactorily with new 60/70 bitumen.Paper presented at the AERC2005. This paper will be part of a special issue of AERC2005.     

Asymmetric logistic peak as a suitable function for the resolution of highly asymmetric voltammograms in non-bilinear systems

The asymmetric logistic peak is tested as a new function for the parametric signal fitting (PSF) of highly asymmetric electrochemical signals in non-bilinear datasets, such as those obtained in linear sweep voltammetry (LSV) or in the presence of irreversible electrochemical processes. This new multivariate curve resolution strategy (PSF-ALPA) is successfully applied to LS voltammograms measured for the Cd(II)-glutathione system with a hanging mercury drop electrode, where Cd(II) is reversibly reduced, and to differential pulse voltammograms (DPV) measured at a glassy carbon electrode, where Cd(II) reduction becomes irreversible. Matrix augmentation by using LS voltammograms measured at different scan rates provides good results and encourages the development of ALPA methodology for third order data.     

Reactivity of Unsaturated 5(4H)-Oxazolones with Hg(II) Acetate: Synthesis of Methyl N-Benzoylamino-3-arylacrylates

An efficient and high-yield procedure to prepare methyl N-benzoylamino-3-arylacrylates from unsaturated (Z)-2-aryl-4-arylidene-5-(4H)-oxazolones and Hg(OAc)₂ in methanol is described herein. The observed reactivity of mercury(II) acetate here is different than its usual metallating behavior and it cleaves the unsaturated oxazolone ring without change of stereochemistry.     

Radial symmetry and symmetry breaking for some interpolation inequalities

We analyze the radial symmetry of extremals for a class of interpolation inequalities known as Caffarelli?CKohn?CNirenberg inequalities, and for a class of weighted logarithmic Hardy inequalities which appear as limiting cases of the first ones. In both classes we show that there exists a continuous surface that splits the set of admissible parameters into a region where extremals are symmetric and a region where symmetry breaking occurs. In previous results, the symmetry breaking region was identified by showing the linear instability of the radial extremals. Here we prove that symmetry can be broken even within the set of parameters where radial extremals correspond to local minima for the variational problem associated with the inequality. For interpolation inequalities, such a symmetry breaking phenomenon is entirely new.     

Sensitive and selective chromogenic sensing of carbon monoxide via reversible axial CO coordination in binuclear rhodium complexes

The study of probes for CO sensing of a family of binuclear rhodium(II) compounds of general formula [Rh(2){(XC(6)H(3))P(XC(6)H(4))}(n)(O(2)CR)(4-n)]·L(2) containing one or two metalated phosphines (in a head-to-tail arrangement) and different axial ligands has been conducted. Chloroform solutions of these complexes underwent rapid color change, from purple to yellow, when air samples containing CO were bubbled through them. The binuclear rhodium complexes were also adsorbed on silica and used as colorimetric probes for "naked eye" CO detection in the gas phase. When the gray-purple colored silica solids containing the rhodium probes were exposed to air containing increasing concentrations of CO, two colors were observed, in agreement with the formation of two different products. The results are consistent with an axial coordination of the CO molecule in one axial position (pink-orange) or in both (yellow). The crystal structure of 3·(CO) ([Rh(2){(C(6)H(4))P(C(6)H(5))(2)}(2)(O(2)CCF(3))(2)]·CO) was solved by single X-ray diffraction techniques. In all cases, the binuclear rhodium complexes studied showed a high selective response to CO with a remarkable low detection limit. For instance, compound 5·(CH(3)CO(2)H)(2) ([Rh(2){(m-CH(3)C(6)H(3))P(m-CH(3)C(6)H(4))(2)}(2)(O(2)CCH(3))(2)]·(CH(3)CO(2)H)(2)) is capable of detection of CO to the "naked eye" at concentrations as low as 0.2 ppm in air. Furthermore, the binding of CO in these rhodium complexes was found to be fully reversible, and release studies of carbon monoxide via thermogravimetric measurements have also been carried out. The importance of the silica support for the maintenance of the CO-displaced L ligands in the vicinity of the probes in a noninnocent manner has been also proved.     

Study of the Complexation of Pb(II) with meso‐2,3‐ Dimercaptosuccinic Acid (DMSA) and 2,3‐Dimercapto‐1‐propanesulfonic acid (DMPS) Using a Bismuth‐Bulk Rotating Disk Electrode

For the first time, the suitability of bismuth bulk rotating disk electrode (BiB‐RDE) for the study of metal complexation has been tested. Cyclic (CV) and differential pulse (DPV) voltammetry have been used to study the complexation of Pb(II) with two of the most effective chelating agents for the treatment of Pb(II) poisoning (meso‐2,3‐dimercaptosuccinic acid, DMSA, and 2,3‐dimercapto‐1‐propanesulfonic acid, DMPS). Multivariate curve resolution has been applied to voltammetric data to obtain the stoichiometries and stability constants of the complexes formed. In both systems, the ML₂ complex was predominant, with log β₂ values of 10.13 and 8.80 for DMSA‐Pb(II) and DMPS‐Pb(II), respectively.