Miguel A. Teixeira

Solvatochromic relationship: prediction of distribution of ionic solutes in aqueous two-phase systems.

Partition ratios of several ionic compounds in 20 different polymer/polymer aqueous two-phase systems (ATPS) containing 0.15 M NaCl in 0.01 M phosphate buffer, pH 7.4, were determined. The differences between the electrostatic properties of the phases in all the ATPS were estimated from partitioning of the homologous series of dinitrophenylated-amino acids. Also the solvatochromic solvent parameters characterizing the solvent dipolarity/polarizability (π*), solvent hydrogen-bond donor acidity (α), and solvent hydrogen-bond acceptor basicity (β) of aqueous media were measured in the coexisting phases of the ATPS. The solute-specific coefficients for the compounds examined were determined by the multiple linear regression analysis using the modified linear solvation energy relationship equation. The minimal number of ATPS necessary for determination of the coefficients was established and 10 ATPS were selected as a reference ATPS set. The solute-specific coefficients values obtained with this reference set of ATPS were used to predict the partition ratios for the compounds in 10 ATPS not included in the reference set. The predicted partition ratios values were compared to those determined experimentally and found to be in good agreement. It is concluded that the presented model of solute-solvent interactions as the driving force for solute partitioning in polymer/polymer ATPS describes experimental observations with 90-95% accuracy.

Study of organic compounds–water interactions by partition in aqueous two-phase systems

Partition coefficients of fourteen organic compounds were determined in 10 or 20 different polymer/polymer aqueous two-phase systems (ATPS) all at physiological pH (0.15M NaCl in 0.01M phosphate buffer, pH 7.4). Solute-specific coefficients characterizing different types of solute-water interactions for the compounds examined were determined by the multiple linear regression analysis. It is shown that (i) the partition behavior for the polar organic compounds is affected not only by dipole-dipole and hydrogen-bond interactions with aqueous environment but, notably, in most cases also by dipole-ion interactions; (ii) it is possible to predict partition behavior for compounds with pre-determined solute-specific coefficients in ATPS with characterized solvent features; and (iii) linear combinations of the solute-specific coefficients for the organic compounds might be useful in the development of quantitative structure-activity relationship (QSAR) analysis to describe their odor detection threshold.

Automatic control of the NMB level in general anaesthesia with a switching total system mass control strategy.

This paper presents a model based switching control strategy to drive the neuromuscular blockade (NMB) level of patients undergoing general anesthesia to a predefined reference. A single-input single-output Wiener system with only two parameters is used to model the effect of two different muscle relaxants, atracurium and rocuronium, and a switching controller is designed based on a bank of total system mass control laws. Each of such laws is tuned for an individual model from a bank chosen to represent the behavior of the whole population. The control law to be applied at each instant corresponds to the model whose NMB response is closer to the patient’s response. Moreover a scheme to improve the reference tracking quality based on the analysis of the patient’s response, as well as, a comparison between the switching strategy and the Extended Kalman Kilter (EKF) technique are presented. The results are illustrated by means of several simulations, where switching shows to provide good results, both in theory and in practice, with a desirable reference tracking. The reference tracking improvement technique is able to produce a better reference tracking. Also, this technique showed a better performance than the (EKF). Based on these results, the switching control strategy with a bank of total system mass control laws proved to be robust enough to be used as an automatic control system for the NMB level.

Design of Perfumes

In this chapter, the Perfumery Ternary Diagram methodology is presented as a tool for the prediction and mapping of the odor character of ternary to quaternary mixtures of fragrance ingredients. To present this methodology, the effect of different base notes in simple fragrance mixtures of the type (top note+middle note+base note and/or+solvent) will be studied to illustrate the potential of this tool. In this study, the selected base notes were three ingredients commonly used in perfumery: vanillin, tonalide, and galaxolide. Moreover, as a proof of concept the PTD® predictive tool is experimentally validated using headspace gas chromatography techniques.

Classification of Perfumes–Perfumery Radar

The qualitative classification of fragrances by words or descriptors is a difficult task, and so its prediction (using any kind of theoretical model) is even more complex. If the former is addressed by experts in perfumery, the latter is mostly considered as utopian, at least in forthcoming years. That is why F&F companies have been doing this job on the basis of sensorial analysis performed by their experienced perfumers, who use multiple (and sometimes complex) odor descriptors to map the olfactory space. However, because the universe is not governed by laws that approach to ideality but instead foresee the increasing of entropy, the way we perceive odor quality varies from person to person and so remains difficult to explain. Consequently, there are significant differences between the classifications obtained from different F&F companies. As a result, once again, human empiric knowledge and expertise rules this job. Altogether, these facts make it virtually impossible to believe in a classification of fragrances with universal acceptance.

Performance of Perfumes

In this chapter, we will address fragrance performance, a very relevant topic for the design of novel and improved fragranced products. Fragrance performance is often assessed by experimental sensory evaluation using panelists, not so by predictive models. Consequently, it introduces human interpersonal variability and increases the time needed for such evaluations. It is no surprise that it would be a tremendous breakthrough to have theoretical models capable of doing so, in seconds.

A Product Engineering Approach in the Perfume Industry

Fragrances are used in a wide variety of daily products like perfumes, cosmetics, toiletries, and household cleaners. The purpose of including fragrances in the formulation of all these different products is to influence consumers, either by enhancing their sensorial properties or simply by signaling the product to be easily recognizable. On their side, consumers are attracted to perfumed products because they are capable of influencing their image, mood, or even their personality. Remarkably, the incorporation of fragrances in products has also the role of improving the evaluations that customers make for the performance of those products: fresh odors are often applied in cleaning products because consumers associate fresh with clean. This bilateral relationship is explained by the power of the sense of olfaction, which surpasses frontiers that other senses cannot reach.