Analysis and finite element simulations of a second‐order fluid model in a bounded domain

This article is concerned with the equations governing the steady motion of a viscoelastic incompressible second‐order fluid in a bounded domain. A new proof of existence and uniqueness of strong solutions is given. In addition, using appropriate finite element methods to approximate a coupled equivalent problem, sharp error estimates are obtained using a fixed point argument. The method is applied to the two‐dimensional lid‐driven cavity problem, at low Reynolds number and in a certain range of values of the viscoelastic parameters, to analyze the combined effects of inertia and viscoelasticity on the flow. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

Patents and literature

Protein engineering and site-directed mutagenesis is becoming immensely important in both fundamental studies and commercial applications involving proteins and enzymes in biocatalysis. Protein engineering has become a powerful tool to help biochemists and molecular enzymologists elucidate structure-function relationships in enzymic active sites, to understand the intricacies of protein folding and denaturation, and to alter the selectivity of enzymatic catalysis. Commercial applications of engineered enzymes are being developed to increase protein stability, widen or narrow substrate specificity, and to develop novel approaches for use of enzymes in organic synthesis, drug design, and clinical applications. In addition to protein engineering, novel expression systems have been designed to prepare large quantities of genetically engineered proteins. Recent US patents and scientific literature on protein engineering, site-directed mutagenesis, and protein expression systems related to protein engineering are surveyed. Patent abstracts are summarized individually and a list of literature references are given.     

Progress in the realisation of an autonomous environmental monitoring device for ammonia

Progress in the development of a micro-fluidic system for colorimetric monitoring of ammonia in drinking and wastewater is described. The ultimate goal is to have a miniaturised instrument that can produce accurate, reliable measurements, is easy to operate, has minimal power consumption, and can operate autonomously for a year. In this study, the indophenol reaction is incorporated into a simple, reliable analytical micro-fluidic system. Absorbance measurements for the blue ammonia-indophenol complex formed in the micro-fluidic system are shown. A key issue is the limiting stability of hypochlorite, a reagent used in the assay. The effects of hypochlorite concentration and impurities on the stability of hypochlorite are investigated and discussed. Decomposition is shown to be very dependent on the presence of heavy-metal impurities. With low levels of these catalytic metals and careful storage, hypochlorite has been shown to be stable for over a year.     

Electrochemical characterisation of a Zn/(PEO)4ZnCl2/Nb2O5 solid-state cell

The (PEO)₄ZnCl₂ electrolyte (PEO, polyethylene oxide) was studied in view of its potential application in a solid-state rechargeable zinc cell. The electrochemical stability window was established, and decomposition voltage values between 3.19 (20 °C) and 1.44 V (150 °C) were estimated. Cyclic voltammetry studies using a Pt/(PEO)₄ZnCl₂/Pt cell indicated reversibility of the Zn²⁺/Zn couple at the electrode/electrolyte interface. Laboratory cells Zn(−)/(PEO)₄ZnCl₂/Nb₂O₅(+) were assembled and studied at 55 °C, under various discharge current densities. Results of cell discharge profiles, capacity values, charge–discharge cycles and cell stabilities are reported.     

Transition Metal-Catalyzed Hydroalkoxylation of Alkynes: An Overview

Oxygen-bearing motifs, mainly the congener heterocycles are ubiquitous due to their presence in various natural products and bioactive scaffolds. Although in literature, several strategies have been developed for their synthesis, hydroalkoxylation of alkynes has come forward as a method of choice and has been used extensively. In particular, hydroalkoxylation of alkynes has gained enormous attention from the synthetic community due to the rapid access to a very useful and reactive synthetic intermediate like ‘enol ether’. Furthermore, to manifold the utility of these methods, reports have been developed elaborating the generation of ‘enol ether’ using hydroalkoxylation and their usage in various reactions in cascade or tandem manner. This review focuses on recent development on the hydroalkoxylation of alkynes for the synthesis of oxygen-containing entities.     

On the optimal control of a class of non-Newtonian fluids

We consider optimal control problems of systems governed by stationary, incompressible generalized Navier–Stokes equations with shear dependent viscosity in a two-dimensional or three-dimensional domain. We study a general class of viscosity functions with shear-thinning and shear-thickening behavior. We prove an existence result for such class of optimal control problems.     

Steady Flows of Shear-Dependent Oldroyd-B Fluids around an Obstacle

This work is concerned with the study of steady flows of an incompressible viscoelastic fluid of Oldroyd type, with viscosity depending on the second invariant of the rate of deformation tensor in an exterior domain. We establish a result of existence and uniqueness of strong solutions for sufficiently small data and give estimates relating these solutions to those of the corresponding generalized Newtonian fluid.     

Evaluation of healthy and sensory indexes of sweetened beverages using an electronic tongue

Overconsumption of sugar-sweetened beverages may increase the risk of health problems and so, the evaluation of their glycemic load and fructose-intolerance level is essential since it may allow establishing possible relations between physiologic effects of sugar-rich beverages and health. In this work, an electronic tongue was used to accurately classify beverages according to glycemic load (low, medium or high load) as well to their adequacy for people suffering from fructose malabsorption syndrome (tolerable or not): 100% of correct classifications (leave-one-out cross-validation) using linear discriminant models based on potentiomentric signals selected by a meta-heuristic simulated annealing algorithm. These results may be partially explained by the electronic tongue’s capability to mimic the human sweetness perception and total acid flavor of beverages, which can be related with glycemic load and fructose-intolerance index. Finally, the E-tongue was also applied to quantify, accurately, healthy and sensory indexes using multiple linear regression models (leave-one-out cross-validation: R_adj > 0.99) in the following dynamic ranges: 4.7 < glycemic load ≤ 30; 0.4 < fructose intolerance index ≤ 1.5; 32 < sweetness perception < 155; 1.3 < total acid flavor, g L⁻¹ < 8.3; and, 5.8 < well-balanced flavor ≤ 74. So, the proposed electronic tongue could be used as a practical, fast, low-cost and green tool for beverage’s healthy and sensory evaluation.     

Mediated and non-mediated electrochemical oxidation of isopropanol

Kinetic studies of the electrochemical generation of Ag(II) and Co(III) ions and the catalytic oxidation of isopropanol in acidic media are presented. Its mediated and non-mediated electrooxidation up to carbon dioxide is considered.