On pairs of regular foliations in R(3) and singularities of map-germs

We study germs of pairs of codimension one regular foliations in R(3) . We show that the discriminant of the pair determines the topological type of the pair. We also consider various classifications of the singularities of the discriminant.

Regular and chaotic interactions of two BPS dyons at low energy

We identify and analyze quasiperiodic and chaotic motion patterns in the time evolution of a classical, non-Abelian Bogomol'nyi-Prasad-Sommerfield (BPS) dyon pair at low energies. This system is amenable to the geodesic approximation which restricts the underlying SU(2) Yang-Mills-Higgs dynamics to an eight-dimensional phase space. We numerically calculate a representative set of long-time solutions to the corresponding Hamilton equations and analyze quasiperiodic and chaotic phase space regions by means of Poincare surfaces of section, high-resolution power spectra and Lyapunov exponents. Our results provide clear evidence for both quasiperiodic and chaotic behavior and characterize it quantitatively. Indications for intermittency are also discussed.

Scaling properties of the regular dynamics for a dissipative bouncing ball model

Some scaling properties of the regular dynamics for a dissipative version of the one-dimensional Fermi accelerator model are studied. The dynamics of the model is given in terms of a two-dimensional nonlinear area contracting map. Our results show that the velocities of saddle fixed points (saddle velocities) can be described using scaling arguments for different values of the control parameter. (c) 2007 Elsevier B.V. All rights reserved.

Toxicity assessment and degradation of disperse azo dyes by photoelectrocatalytic oxidation on Ti/TiO2 nanotubular array electrodes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bisphenol A removal from wastewater using self-organized TIO2 nanotubular array electrodes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Removal of sunscreen compounds from swimming pool water using self-organized TiO2 nanotubular array electrodes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inclusão escolar pela via da colaboração entre educação especial e educação regular

A preocupação sobre as práticas inclusivas nas escolas públicas no Brasil começou após a Declaração de Salamanca, com desafios e dúvidas. Ainda hoje, passados cerca de 15 anos, os professores do ensino regular se queixam dizendo que não têm conhecimento suficiente ou preparo formal para lidar com crianças com necessidades educacionais especiais, especialmente quando estas apresentam disfunções graves, como paralisia cerebral, deficiência intelectual e comportamentos desafiadores. A colaboração entre profissionais da Educação Especial e Regular pode ser uma alternativa para enfrentar tais desafios. O objetivo deste relato foi o de apresentar um breve histórico de um programa de pesquisa, ensino e extensão que busca aproximar a Universidade Federal de São Carlos (UFSCar) dos professores do ensino comum que têm alunos com necessidades especiais em suas salas de aula. Iniciado em 2004, este programa está na atualidade em seu sétimo ano de execução e envolve professores da universidade, estudantes de graduação e pós-graduação e professores do ensino comum. Os resultados parecem apontar essa via de colaboração entre Educação Especial e Regular como um caminho promissor para a construção de escolas mais inclusivas.

Genotoxicity and cytotoxicity of mineral trioxide aggregate and regular and white Portland cements on Chinese hamster ovary (CHO) cells in vitro

Objective. Recently, mineral trioxide aggregate (MTA) and Portland cement have been used in dentistry as root-end-filling materials. However, the reported results concerning the biocompatibility of these materials are inconsistent. The goal of this study was to examine the genotoxicity and cytotoxicity of MTA and Portland cements in vitro by the single-cell gel (comet) assay and trypan blue exclusion test.Study design. Chinese hamster ovary (CHO) cells were exposed to MTA and regular and white Portland cements at final concentration ranging from 1 to 1000 mu g/mL for 1 h at 37 degrees C.Results. All compounds tested did not show genotoxic effects in all concentrations evaluated. No significant differences (P > .05) in cytotoxicity were observed for all compounds tested.Conclusions. Taken together, our results suggest that MTA and Portland cements are not genotoxins and are not able to induce cellular death.

Amperometric differential determination of ascorbic acid in beverages and vitamin C tablets using a flow cell containing an array of gold microelectrodes modified with palladium

A simple and attractive method for quantification of ascorbic acid (AA) in beers, soda, natural juices and commercial vitamin C tablets was achieved by combining Bow injection analysis and amperometric detection. An array of gold microelectrodes electrochemically modified by deposition of palladium was employed as working electrode which was almost unaffected by fouling effects. Ascorbic acid was quantified in beverages and vitamin tablets using amperometric differential measurements. This method is based on three steps involving the flow injection of: 1) the sample plus a standard addition of AA, 2) the pure sample, and 3) the enzymatically-treated sample. The enzymatic treatment was carried out with Cucumis sativus tissue, which is a rich source of ascorbate oxidase, at pH 7. The calibration plots for freshly prepared ascorbic acid standards were very linear in the concentration range of 0.18-1.8 mg L-1 with a relative standard deviation (RSD) < 1%, while for real samples the deviations were between 2.7% to 8.9%.

Validation of an immunoassay method for the determination of traces of carbaryl in vegetable and fruit extracts by liquid chromatography with photodiode array and mass spectrometric detection

A competitive enzyme-linked immunosorbent assay (ELISA) method for carbaryl quantitation in crop extracts was validated by liquid chromatography (LC) with diode array detection (DAD). For this purpose, six crops (banana, carrot, green bean, orange, peach and potato) were chosen for recovery and reproducibility studies. The general sample preparation included extraction with methanol followed by liquid-liquid partitioning and clean-up on Celite-charcoal adsorbent column of the vegetable extracts. ELISA samples consisted of a diluted LC extract in assay phosphate buffer (pH 7.5). The potential effect of methanol in these samples was evaluated. It was observed that a maximum content of 10% methanol present in the assay buffer could be tolerated without expressive losses in the ELISA performance. Under these conditions, a IC50 similar to 1.48 mu g l(-1) was obtained. A minimum matrix effect with a 1:50 dilution of the methanolic extracts in assay buffer was noticed, except for green bean samples that inhibited completely the assay. For the vegetable extracts, the ELISA sensitivities varied from 3.9 to 5.7 mu g l(-1), and good recoveries (82-96%) with R.S.D.s ranging from 5.7 to 12.1% were found. An excellent correlation between the LC-DAD and ELISA techniques was obtained. The confirmation of the carbaryl in less concentrated samples was achieved by LC-mass spectrometry interfaced with atmospheric pressure chemical ionisation. The [M + H](+)= 202 and [M + H-57](+)=145 ions, equivalent to the protonated molecular and l-naphthol ions, respectively, were used to carbaryl identification in these samples. (C) 1998 Elsevier B.V. B.V. All rights reserved.

Flow-through cell based on an array of gold microelectrodes obtained from modified integrated circuit chips

The construction of a flow-through cell incorporating an array of gold microelectrodes is described and its application to flow injection analysis with amperometric detection is presented, Simple modification of almost any conventional integrated circuit chip, used as an inexpensive source of pre-assembled gold micro-wires, leads to the rapid and successful preparation of arrays of 8-48 elements, the polymeric encapsulation material from the top face of the chip is removed by abrasion until the gold micro-mires (used to interconnect the silicon circuit to the external contact pins of the chip) are disrupted and their transversal (elliptical) sections become exposed. Once polished, the flat and smooth top surface of the gold microelectrode-array chip (MEAC) is provided with a spacer and fitted under pressure against an acrylic block with the reference and auxiliary electrodes, to form the electrochemical (thin-layer) flow cell, while the contact pins are plugged into a standard IC socket, This design ensures autonomous electric contact with each electrode and allows fast dismantling for polishing or substitution, the performance of flow cells with MEACs was investigated utilizing the technique of reverse pulse amperometry without oxygen removal, A method was established for the determination of the copper concentration in sugar cane spirit, regulated by law for beverages, Samples from industrial producers and small-scale (alembic) brewers were compared, With a 24 MEAC, a detection limit of 30 mu g I-l of copper (4.7 x 10(-7) mol l(-1) of Cu-II for 100 mu l injections) was calculated, Routine operation was established at a frequency of 60-90 determinations per hour, Intercomparison with atomic absorption spectrometric determinations resulted in excellent agreement.

Determination of rice herbicides, their transformation products and clofibric acid using on-line solid-phase extraction followed by liquid chromatography with diode array and atmospheric pressure chemical ionization mass spectrometric detection

A simultaneous method for the trace determination of acidic, neutral herbicides and their transformation products in estuarine waters has been developed through an on-line solid-phase extraction method followed by liquid chromatography with diode array and mass spectrometric detection. An atmospheric pressure chemical ionization (APCI) interface was used in the negative ionization mode after optimization of the main APCI parameters. Limits of detection ranged from 0.1 to 0.02 ng/ml for 50 mi of acidified estuarine waters preconcentrated into polymeric precolumns and using time-scheduled selected ion monitoring mode. Two degradation products of the acidic herbicides (4-chloro-2-methylphenol and 2,4-dichlorophenol) did not show good signal response using APCI-MS at the concentration studied due to the higher fragmentor voltage needed for their determination For molinate and the major degradation product of propanil, 3,4-dichloroaniline, positive ion mode was needed for APCI-MS detection. The proposed method was applied to the determination of herbicides in drainage waters from rice fields of the Delta del Ebro (Spain). During the S-month monitoring of the herbicides, 8-hydroxybentazone and 4-chloro-2-methylphenoxyacetic acid were successively found in those samples. (C) 2000 Elsevier B.V. B.V. All rights reserved.

On a regular convex solver potential for an elastic-damage constitutive model: a theoretical analysis

This work is related with the proposition of a so-called regular or convex solver potential to be used in numerical simulations involving a certain class of constitutive elastic-damage models. All the mathematical aspects involved are based on convex analysis, which is employed aiming a consistent variational formulation of the potential and its conjugate one. It is shown that the constitutive relations for the class of damage models here considered can be derived from the solver potentials by means of sub-differentials sets. The optimality conditions of the resulting minimisation problem represent in particular a linear complementarity problem. Finally, a simple example is present in order to illustrate the possible integration errors that can be generated when finite step analysis is performed. (C) 2003 Elsevier Ltd. All rights reserved.

Dinuclear Azide-Bridged Copper(II) Complex as Building Block for the Assembly of a 2D-Supramolecular Array

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)