Aplicação do ultra-som em sistemas eletroquímicos: considerações teóricas e experimentais

The aim of this review is to present and discuss the applications of ultrasound in electrochemical systems such as in sonoelectroanalysis and sonoelectrolysis for the electrochemical combustion of organic compounds. Initially, theoretical and experimental aspects are discussed, particularly those related to the enhancement of mass transport and the surface cleaning effects. Some results are included to illustrate alternative geometries for the experimental measurements and the working electrodes used in these systems. In the sequence, the available publications are presented and discussed to demonstrate that ultrasound combined with electrochemical techniques is a powerful set-up for the detection of analytes such as metals and/or organic compounds in hostile media and for the effective destruction of toxic organic substances. At the end, a table summarizes the results already published in the literature.

Influência de diferentes sistemas de solvente água-etanol sobre as propriedades físico-químicas e espectroscópicas dos compostos macrocíclicos feofitina e clorofila α

This work focus on the influence of solvent on the photophysical properties of chlorophyll α and pheophytin. Both compounds are related to the photosynthesis process and are considered prototypes of photosensitizers in Photodynamic Therapy. Fluorescence measurements were developed using water/ethanol mixtures at different compositions, since both solvents could be employed in biological applications. The spectroscopic properties of these compounds undergo profound changes depending on water content in the ethanol due to auto-aggregation processes. The major hydrophobicity and the lower dielectric constant of ethanol when compared with water precluded significantly the auto-aggregation process of these compounds.

A novel disposable electrochemical microcell: construction and characterization

An alternative technique for the fabrication of disposable electrochemical microcells containing working, reference and auxiliary electrodes on a single device is reported. The procedure is based on thermal-transfer of toner masks onto CD-R (recordable compact discs) gold surfaces to define the layout of the electrodes (contour). In a subsequent step, the layout is manually painted with a permanent marker pen. The unprotected gold surface is conveniently etched (chemical corrosion) and the ink is then easily removed with ethanol, generating gold surfaces without contamination. The final and reproducible area of the electrodes is defined by heat transference of a second toner mask. Silver epoxy is deposited on one of the gold bands which is the satisfactorily used as reference electrode. These microcells were electrochemically characterized by cyclic, linear, and square wave voltammetry, and several electroactive species were used as model systems. The area reproducibility of the electrodes for different microcells was studied and a relative standard deviation better than 1,0% (n = 10) was obtained. Disposable electrochemical microcells were successfully used in analysis of liquid samples with volumes lower than 200 µL and good stability and reproducibility (RSD less than 2.0%) were achieved. These microcells were also evaluated for quantification of paracetamol and dipyrone in pharmaceutical formulations.

Uso de sistemas de informação geográfica em campanhas de vacinação contra a raiva

OBJETIVO: Desenvolver método para planejamento e avaliação de campanhas de vacinação contra a raiva animal. MÉTODOS: O desenvolvimento da metodologia baseou-se em sistemas de informação geográfica para estimar a população e a densidade animal (canina e felina) por setores censitários e subprefeituras do município de São Paulo, em 2002. O número de postos de vacinação foi estimado para atingir uma dada cobertura vacinal. Foram utilizadas uma base de dados censitários para a população humana, e estimativas para razões cão:habitante e gato:habitante. RESULTADOS: Os números estimados foram de 1.490.500 cães e 226.954 gatos em São Paulo, uma densidade populacional de 1.138,14 animais domiciliados por km². Foram vacinados, na campanha de 2002, 926.462 animais, garantindo uma cobertura vacinal de 54%. O número total estimado de postos no município para atingir uma cobertura vacinal de 70%, vacinando em média 700 animais por posto foi de 1.729. Estas estimativas foram apresentadas em mapas de densidade animal, segundo setores censitários e subprefeituras. CONCLUSÕES: A metodologia desenvolvida pode ser aplicada de forma sistemática no planejamento e no acompanhamento das campanhas de vacinação contra a raiva, permitindo que sejam identificadas áreas de cobertura vacinal crítica.

Características de carcaça de ovelhas de descarte das raças Ideal e Texel terminadas em dois sistemas de alimentação

Avaliaram-se as características de carcaça de ovelhas de descarte das raças Ideal e Texel terminadas em dois sistemas de alimentação. Utilizaram-se 20 ovelhas (10 da raça Ideal e 10 da raça Texel) aleatoriamente distribuídas de acordo com o grupo genético em dois manejos alimentares (confinamento e pastagem cultivada). Os abates foram realizados quando os animais atingiram 3,5 pontos de condição corporal. Os pesos de carcaça quente (PCQ) e de carcaça fria (PCF) e os rendimentos de carcaça quente (RCQ) e de carcaça fria (RCF) das ovelhas Texel foram maiores que os das ovelhas Ideal: 27,85 e 19,04 kg; 27,08 e 18,43 kg; 47,25 e 45,20% e 45,95 e 43,72%, respectivamente. O peso dos cortes perna, paleta, pescoço e costela e os pesos de músculos, ossos e gordura da perna dos animais da raça Texel foram superiores aos obtidos na raça Ideal. Quando avaliadas em porcentagem do peso corporal, no entanto, essas características não diferiram entre as duas raças. O manejo alimentar não influenciou as características de carcaça de ovelhas de descarte. Ovelhas Texel apresentam cortes maiores que os de ovelhas Ideal.

Sistemas informatizados de registro de imunização: uma revisão com enfoque na saúde infantil

São apresentadas diferentes experiências e metodologias empregadas por registros informatizados de imunização (RII), no enfoque da saúde infantil. O levantamento bibliográfico abrangeu publicações de 1990 a 2006, existentes nas bases MEDLINE, SciELO, PubMed e EMBASE. Outros sítios eletrônicos de organizações nacionais e internacionais de saúde foram pesquisados. Em virtude da ausência de publicações sobre RII no Brasil, as fontes de informação foram a Coordenação Nacional e as Coordenações Estaduais do Programa Nacional de Imunizações, além do Departamento de Informática do Sistema Único de Saúde. Selecionaram-se apenas artigos que abordam RII em saúde infantil. Foram localizados 109 artigos publicados em 35 revistas especializadas. São apresentados aspectos históricos e conceituais, objetivos, funções, relevância e indicadores de desempenho e de custo-efetividade, além das próprias limitações dos RII, assim como experiências em países selecionados, inclusive no Brasil. Os RII integrados a outros sistemas de informação vêm sendo aplicados como importante instrumento para a identificação de populações com menor acesso ou adesão aos programas de vacinação e em sistemas de vigilância ativa de eventos adversos pós-vacina

A positional FEM Formulation for geometrical non-linear analysis of shells

This work presents a fully non-linear finite element formulation for shell analysis comprising linear strain variation along the thickness of the shell and geometrically exact description for curved triangular elements. The developed formulation assumes positions and generalized unconstrained vectors as the variables of the problem, not displacements and finite rotations. The full 3D Saint-Venant-Kirchhoff constitutive relation is adopted and, to avoid locking, the rate of thickness variation enhancement is introduced. As a consequence, the second Piola-Kirchhoff stress tensor and the Green strain measure are employed to derive the specific strain energy potential. Curved triangular elements with cubic approximation are adopted using simple notation. Selected numerical simulations illustrate and confirm the objectivity, accuracy, path independence and applicability of the proposed technique.

Modelo de programação linear para otimização econômica do projeto de irrigação Baixo Acaraú - CE

The present work had as objective uses a model of lineal programming algorithm to optimize the use of the water in the District of Irrigation Baixo Acarau-CE proposing the best combination of crop types and areas established of 8,0 ha. The model aim maximize the net benefit of small farmer, incorporating the constraints in water and land availability, and constraints on the market. Considering crop types and the constraints, the study lead to the following conclusions: 1. The water availability in the District was not a limiting resources, while all available land was assigned in six of the seven cultivation plans analyzed. Furthermore, water availability was a restrictive factor as compared with land only when its availability was made to reduce to 60% of its actual value; 2. The combination of soursop and melon plants was the one that presented the largest net benefit, corresponding to R$ 5,250.00/ha/yr. The planting area for each crop made up to 50% of the area of the plot; 3. The plan that suggests the substitution of the cultivation of the soursop, since a decrease in annual net revenue of 5.87%. However, the plan that contemplates the simultaneous substitution of both soursop and melon produced the lowest liquid revenue, with reduction of 33.8%.

Identification of a Highly Antigenic Linear B Cell Epitope within Plasmodium vivax Apical Membrane Antigen 1 (AMA-1)

Apical membrane antigen 1 (AMA-1) is considered to be a major candidate antigen for a malaria vaccine. Previous immunoepidemiological studies of naturally acquired immunity to Plasmodium vivax AMA-1 (PvAMA-1) have shown a higher prevalence of specific antibodies to domain II (DII) of AMA-1. In the present study, we confirmed that specific antibody responses from naturally infected individuals were highly reactive to both full-length AMA-1 and DII. Also, we demonstrated a strong association between AMA-1 and DII IgG and IgG subclass responses. We analyzed the primary sequence of PvAMA-1 for B cell linear epitopes co-occurring with intrinsically unstructured/ disordered regions (IURs). The B cell epitope comprising the amino acid sequence 290-307 of PvAMA-1 (SASDQPTQYEEEMTDYQK), with the highest prediction scores, was identified in domain II and further selected for chemical synthesis and immunological testing. The antigenicity of the synthetic peptide was identified by serological analysis using sera from P. vivax-infected individuals who were knowingly reactive to the PvAMA-1 ectodomain only, domain II only, or reactive to both antigens. Although the synthetic peptide was recognized by all serum samples specific to domain II, serum with reactivity only to the full-length protein presented 58.3% positivity. Moreover, IgG reactivity against PvAMA-1 and domain II after depletion of specific synthetic peptide antibodies was reduced by 18% and 33% (P = 0.0001 for both), respectively. These results suggest that the linear epitope SASDQPTQYEEEMTDYQK is highly antigenic during natural human infections and is an important antigenic region of the domain II of PvAMA-1, suggesting its possible future use in pre-clinical studies.

Matter-wave two-dimensional solitons in crossed linear and nonlinear optical lattices

The existence of multidimensional matter-wave solitons in a crossed optical lattice (OL) with a linear optical lattice (LOL) in the x direction and a nonlinear optical lattice (NOL) in the y direction, where the NOL can be generated by a periodic spatial modulation of the scattering length using an optically induced Feshbach resonance is demonstrated. In particular, we show that such crossed LOLs and NOLs allow for stabilizing two-dimensional solitons against decay or collapse for both attractive and repulsive interactions. The solutions for the soliton stability are investigated analytically, by using a multi-Gaussian variational approach, with the Vakhitov-Kolokolov necessary criterion for stability; and numerically, by using the relaxation method and direct numerical time integrations of the Gross-Pitaevskii equation. Very good agreement of the results corresponding to both treatments is observed.

Linear and nonlinear transport in a small charge-tunable open quantum ring

We experimentally study the Aharonov-Bohm-conductance oscillations under external gate voltage in a semiconductor quantum ring with a radius of 80 nm. We find that, in the linear regime, the resistance-oscillation plot in the voltage-magnetic-field plane corresponds to the quantum ring energy spectra. The chessboard pattern assembled by resistance diamonds, while loading the ring, is attributed to a short electron lifetime in the open configuration, which agrees with calculations within the single-particle model. Remarkably, the application of a small dc current allows observing strong deviations in the oscillation plot from this pattern accompanied by a magnetic-field symmetry break. We relate such behavior to the higher-order-conductance coefficients determined by electron-electron interactions in the nonlinear regime.

GLOBAL WELL-POSEDNESS AND NON-LINEAR STABILITY OF PERIODIC TRAVELING WAVES FOR A SCHRODINGER-BENJAMIN-ONO SYSTEM

The objective of this paper is two-fold: firstly, we develop a local and global (in time) well-posedness theory for a system describing the motion of two fluids with different densities under capillary-gravity waves in a deep water flow (namely, a Schrodinger-Benjamin-Ono system) for low-regularity initial data in both periodic and continuous cases; secondly, a family of new periodic traveling waves for the Schrodinger-Benjamin-Ono system is given: by fixing a minimal period we obtain, via the implicit function theorem, a smooth branch of periodic solutions bifurcating a Jacobian elliptic function called dnoidal, and, moreover, we prove that all these periodic traveling waves are nonlinearly stable by perturbations with the same wavelength.

Definindo a arena política local: sistemas partidários municipais na federação brasileira

This article analyzes the Brazilian political system from the local perspective. Following Cox (1997), we review the problems with electoral coordination that emerge from a given institutional framework. Due to the characteristics of the Brazilian Federal system and its electoral rules, linkage between the three levels of government is not guaranteed a priori, but demands a coordinating effort by the parties' leadership. According to our hypothesis, the parties are capable of coordinating their election strategies at different levels in the party system. Regression models based on two-stage least squares (2SLS) and TOBIT, analyzing a panel of Brazilian municipalities with data from the 1994 and 2000 elections, show that the proportion of votes received by a party in a given election correlates closely with its previous votes in majoritarian elections. Despite institutional incentives, the Brazilian party system shows evidence that it is organized nationally to the extent that it links the competition for votes at the three levels of government (National, State, and Municipal).

A nearly optimum linear-phase digital FIR filters design

A new simple method to design linear-phase finite impulse response (FIR) digital filters, based on the steepest-descent optimization method, is presented in this paper. Starting from the specifications of the desired frequency response and a maximum approximation error a nearly optimum digital filter is obtained. Tests have shown that this method is alternative to other traditional ones such as Frequency Sampling and Parks-McClellan, mainly when other than brick wall frequency response is required as a desired frequency response. (C) 2011 Elsevier Inc. All rights reserved.

Non-linear boundary element formulation applied to contact analysis using tangent operator

This work presents a non-linear boundary element formulation applied to analysis of contact problems. The boundary element method (BEM) is known as a robust and accurate numerical technique to handle this type of problem, because the contact among the solids occurs along their boundaries. The proposed non-linear formulation is based on the use of singular or hyper-singular integral equations by BEM, for multi-region contact. When the contact occurs between crack surfaces, the formulation adopted is the dual version of BEM, in which singular and hyper-singular integral equations are defined along the opposite sides of the contact boundaries. The structural non-linear behaviour on the contact is considered using Coulomb`s friction law. The non-linear formulation is based on the tangent operator in which one uses the derivate of the set of algebraic equations to construct the corrections for the non-linear process. This implicit formulation has shown accurate as the classical approach, however, it is faster to compute the solution. Examples of simple and multi-region contact problems are shown to illustrate the applicability of the proposed scheme. (C) 2011 Elsevier Ltd. All rights reserved.