Disposable Graphite Foil Based Electrodes and Their Application in Pharmaceutical Analysis

This paper explores a new source of graphite for working electrodes, which presents advantages such as low electrical resistance, good flexibility, favorable mechanical performance, versatility to design electrodes in almost any size and very low cost. The new electrodes were investigated in batch electrochemical cells as associated with flow injection analysis systems. Cyclic voltammetry, stripping voltammetry, and amperometry associated with flow injection analysis techniques were applied for the determination of ascorbic acid, zinc and paracetamol in pharmaceutical formulations, respectively. Well‐established analytical methods were applied for comparison purposes. The results herein demonstrate the potential of graphite foils as working electrodes in different electroanalytical methods, offering the possibility of producing disposable sensors for routine applications.     

On the efficiency and quality of numerical solutions in CFD problems using the interface strip preconditioner for domain decomposition methods

In this paper, some pathologies found for simple tests solved by means of preconditioned full iterative schemes are presented. According to these results (Sections 4 and 5), the accuracy deterioration observed should be considered as a warning for the final application given to these solutions. Even though it is well known that full iterative solvers are not the best selection for comparison, they were chosen because they are widely used by the computational fluid dynamic (CFD) community for a diversity of complex fluid dynamics applications. FEM simulated solutions are compared with analytical solutions or measured data for problems that have been considered as ‘benchmarks’ in the CFD literature. For this purpose, the study of the solution obtained via parallelized iterative methods that have been extensively used (e.g. conjugate gradients (CG), GMRes global iteration and its variants, ‘overlapping’ and ‘non‐overlapping’ additive Schwarz domain decomposition schemes) in CFD computations and those obtained with the new interface strip preconditioner (J. Comput. Meth. Sci. Engng 2003; Int. J. Numer. Meth. Engng 2005; 62 (13):1873–1894) for the Schur complement method is carried out. The idea is to present the new solver as an alternative to obtain more accurate and faster solutions in the context of monolithic and non‐monolithic schemes applied to a internal/external viscous compressible/incompressible flows around bodies of complex shapes. Therefore, the target of this work is to show how the reliability of CFD codes is affected by the solver selection and why domain decomposition methods should be viewed not only as a more efficient strategy, but also to guarantee the solution quality. Copyright © 2006 John Wiley & Sons, Ltd.     

Lupeol

The title compound [systematic name: 3β‐lup‐20(29)‐en‐3‐ol], C₃₀H₅₀O, was isolated from the leaves of Garcinia brasiliensis (common name: bacupari; a member of the Guttiferae family) and has been shown to have many useful medicinal and biological properties. The lupeol molecule consists of four six‐membered rings (adopting chair conformations) and one five‐membered ring (with an envelope conformation), all fused in trans fashion. Lupeol is isomorphic with the pentacyclic triterpene 3β,30‐dihydroxylup‐20(29)‐ene, which differs from lupeol due to the presence of an additional hydroxy group. The crystal packing is stabilized by van der Waals interactions and intermolecular O—H...O hydrogen bonds, giving rise to an infinite helical chain along the c axis.     

Markovian networks in labour markets

In labour theory, equilibrium is described in terms of mean variables, which is limited and can be misleading. In this article, we model the labour market as a closed Markovian network and find the steady state distribution of unemployment and advertised vacancies. We determine the stochastic equilibrium distribution for two different types of matching functions and allow for both unemployed and on the job search. In general cases, where probabilities cannot be analytically computed, we find restrictions that must hold for all matching processes. Our modelling is applicable to most economic markets with frictions.     

Gradient Estimates for the Ground State¶Schrödinger Eigenfunction and Applications

Let Ω be a planar convex domain which is symmetric with respect to each coordinate axes. In this paper we give a simple and very short proof, based on the maximum principle, of the sharp lower bound for the spectral gap of the Dirichlet Laplacian in Ω. Received: 21 May 2001 / Accepted: 29 June 2001     

Information encryption through dyadic permutations

Dyadic displacements of an image can be interpreted as a special type of permutations of its pixel addresses. Owing to this property, they can be used to encrypt the information contained in the pictures without information loss or damage. The information recovery can be performed successfully by using dyadic correlations.     

Low‐Level Laser Therapy and Sodium Diclofenac in Acute Inflammatory Response Induced by Skeletal Muscle Trauma: Effects in Muscle Morphology and mRNA Gene Expression of Inflammatory Markers

Pharmacological therapy is widely used in the treatment of muscle injuries. On the other hand, low‐level laser therapy (LLLT) arises as a promising nonpharmacological treatment. The aim of this study was to analyze the effects of sodium diclofenac (topical application) and LLLT on morphological aspects and gene expression of biochemical inflammatory markers. We performed a single trauma in tibialis anterior muscle of rats. After 1 h, animals were treated with sodium diclofenac (11.6 mg g^‐1 of solution) or LLLT (810 nm; continuous mode; 100 mW; 3.57 W cm^?2; 1, 3 or 9 J; 10, 30 or 90 s). Histological analysis and quantification of gene expression (real‐time polymerase chain reaction—RT‐PCR) of cyclooxygenase 1 and 2 (COX‐1 and COX‐2) and tumor necrosis factor‐alpha (TNF‐α) were performed at 6, 12 and 24 h after trauma. LLLT with all doses improved morphological aspects of muscle tissue, showing better results than injury and diclofenac groups. All LLLT doses also decreased (P < 0.05) COX‐2 compared to injury group at all time points, and to diclofenac group at 24 h after trauma. In addition, LLLT decreased (P < 0.05) TNF‐α compared both to injury and diclofenac groups at all time points. LLLT mainly with dose of 9 J is better than topical application of diclofenac in acute inflammation after muscle trauma.     

1,1-Diamino-2-nitroethylenes as excellent hydrogen bond donor organocatalysts in the Michael addition of carbon-based nucleophiles to β-nitrostyrenes

A new class of hydrogen bond donor catalysts based on the 1,1-diamino-2-nitroethylene scaffold has been introduced for the activation of trans-β-nitrostyrenes toward reactions with a range of carbon-based nucleophiles, affording the corresponding adducts in excellent yields. Importantly, this new set of organocatalysts is easily prepared from commercially available starting materials in mild reaction conditions.