CHARACTERIZATION of RALSTONIA SOLANACEARUM STRAINS FROM BRAZIL USING MOLECULAR METHODS and PATHOGENICITY TESTS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da geometria e da temperatura na cinética de secagem de tomate (Lycopersicum esculentum)

O tomate é um fruto muito perecível por causa do seu conteúdo de umidade. A secagem é uma das práticas industriais mais utilizadas em alimentos para manter a qualidade do produto final. A pesquisa foi desenvolvida para estudo dos parâmetros de secagem de tomate (Lycopersicon esculentum Mill), cv Carmen, com relação ao tipo de corte (meio e um quarto) e à temperatura de processo (60 e 70 ºC), bem como à escolha do tempo de secagem para a obtenção de um produto com umidade de 45% (base úmida). As cinéticas de secagem foram determinadas experimentalmente por convecção forçada e ajustadas ao modelo de Page. Os resultados obtidos mostraram que a geometria de corte influenciou na taxa de secagem e no tempo de desidratação. Os tomates cortados em quatro partes e desidratados a 70 ºC alcançaram umidade de 45% em menor tempo (10 horas), quando comparados aos tomates com o corte em metades. O modelo de Page forneceu bom ajuste nas cinéticas de secagem

Study of the potentiometric response of the doped spinel Li1.05Al0.02Mn1.98O4 for the optimization of a selective lithium ion sensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Voltammetric performance and application of a sensor for sodium ions constructed with layered birnessite-type manganese oxide

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development of an electrochemical sensor for potassium ions based on KSr(2)Nb(5)O(15) modified electrode

In the work described by this paper, we studied the development of a selective potassium ion sensor constituted of a carbon paste electrode modified (CPEM) with a novel KSr(2)Nb(2)O(15). The material KSr(2)Nb(2)O(15) is an oxide with the tetragonal tungsten bronze structure (TTB) type are in forefront both in the area of research as well as in industrial applications. The sensor response to potassium ions was linear in the concentration range 1.26 x 10(-5) at 1.62 x 10(-3) mol L(-1) (E (mV) = 32.7 + 51.1 log [K(+)]). The sensor based KSr(2)Nb(2)O(15), of the TTB-type presented very good potentiometric response, with a slope of 51.1 mV/dec (at 25 degrees C) and detection limit for the potassium ions of 7.27 x 10(-5) mol.L(-1)

Mutagenic Activity of Glycoallkaloids from Solanum palinacanthum Dunal (Solanaceae) in the Brazilian cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito da concentração do amido de milho na liberação de paracetamol de comprimidos

Este trabalho avaliou a influência da concentração de amido de milho nas características físicas e na liberação in vitro de paracetamol a partir de comprimidos. Os granulados foram analisados quanto à granulometria e densidades aparentes bruta e compactada e os comprimidos quanto ao peso médio, espessura, dureza, friabilidade, tempo de desintegração. Os comprimidos foram preparados a partir de granulados obtidos por granulação a úmido, utilizando cozimento de amido a 10% como agente granulante, segundo três formulações. Embora os comprimidos obtidos tenham apresentado características dentro dos limites farmacopéicos, os resultados indicam que variações da concentração de amido provocam diferenças nos diversos parâmetros físicos estudados. Concentração mais alta de amido em pó dá origem, provavelmente, à interação entre os componentes da fórmula, interferindo na liberação in vitro do fármaco. Isto demonstra a importância de se otimizar a concentração dos adjuvantes numa formulação de comprimidos, pois, embora uma pequena variação nesta concentração não exerça efeito significativo no tempo de desintegração, a quantidade de fármaco liberado pode ser substancialmente alterada.

Adsorption and detection of DNA dendrimers at carbon electrodes

Dendritic nucleic acids are highly branched and ordered molecular structures, possessing numerous single-stranded oligonucleotide arms, which hold great promise for enhancing the sensitivity of DNA biosensors. This article evaluates the interfacial behavior and redox activity of nucleic acid dendrimers at carbon paste electrodes, in comparison to DNA. Factors influencing the adsorption behavior, including the adsorption potential and time, solution conditions, or dendrimer concentration, are explored. The strong adsorption at the anodically pretreated carbon surface is exploited for an effective preconcentration step prior to the chronopotentiometric measurement of the surface species. Coupled with the numerous guanine oxidation sites, such stripping protocol offers remarkably low detection limits (e.g., 3 pM or 2.4 femtomole of the I-layer dendrimer following a 15 min accumulation). The new observations bear important implications upon future biosensing applications of nucleic dendrimers.

Indicator-free electrochemical DNA hybridization biosensor

A new electrochemical hybridization biosensor protocol without an external indicator is described. The biosensor format involves the immobilization of inosine-substituted (guanine-free) probe onto the carbon paste transducer, and a direct chronopotentiometric detection of the duplex formation by the appearance of the guanine oxidation peak of the target. Such a use of the intrinsic DNA electrochemical response for monitoring hybridization events offers several advantages (over the common use of external indicators), including the appearance of a new peak, a Aat background, or simplicity. A 4 min short hybridization period allows a detection limit around 120 ng/ml. Performance characteristics of the sensor are described along with future prospects. (C) 1998 Elsevier B.V. B.V. All rights reserved.

Tomate salada: uma alternativa como fonte de antioxidante para uso tópico

Tomato Salad: An Alternative as Antioxidant Source for Topic Use. Tomato is the principal source of lycopene, a carotenoid with high antioxidant activity which can be used topically as a phytocosmetic to combat skin aging. The aim of this study was to get a lycopene-rich extract from salad tomato pulp. The extract was analyzed using UV/vis spectroscopy, thin layer chromatography and high performance liquid chromatography. Oxidant activity was analyzed using the free radical DPPH method. The presence of lycopene in the salad tomato was confirmed. It was present in the apolar fraction rich in carotenoids, which was 96.70% lycopene. In the evaluation of the antioxidant activity, using the radical DPPH, the extract showed activity (IC(50) = 0,311 mg/mL). We conclude that the salad tomato can be used as a source of antioxidants for topic use.

Influência da adição no comportamento reológico da pasta autoadensável de alto desempenho

Influence of admixture on the rheological behavior of high performance self-compacting paste. This research proposes to study the influence of the specific area, mould and surface texture of admixtures on the rheological behavior of high performance self-compacting paste (HPSCP). The selected admixtures are calcareous filler and basalt filler, which are industrial residues, thus contributing to sustainable development. The paste is made up of cement, silica fume, calcareous filler or basalt filler, water and superplasticizer additive. For this study, the water/cement ratios are fixed = 0.40 L kg(-1); silica fume/cement = 0.10 kg kg(-1); the filler/cement and superplasticizer/cement ratios are determined through Marsh cone and mini-slump tests. The results show that for same filler/cement ratios, the ratios of superplasticizer to paste with calcareous filler are significantly lower than those of paste with basalt filler. The results show that the specific area, mould and surface texture of these admixtures significantly influence the rheological behavior of HPSCP.

Encapsulation of titanium (IV) silsesquioxane into the NH4USY zeolite: Preparation, characterization and application

This work describes the encapsulation of titanium (IV) silsesquioxane into the supercavities of NH4USY ultra stabilized zeolite, after chemical treatment. The modified zeolite was characterized by Fourier transform infrared spectra, Nuclear magnetic resonance, scanning electronic microscopy, X-ray diffraction and thermogravity. This encapsulated titanium (IV) silsesquioxane can adsorb Azure A chloride after treatment with H3PO4, without modifier leaching problems. In an electrochemical study, the cyclic voltammograms of the graphite paste modified electrode, shows two redox couples with formal potential (E-0) -0. 1 V and 0.21 V to I and II redox couples respectively (v = 700 mV s(-1); Britton Robinson buffer (B-R) solution, pH 3) versus SCE ascribed to a monomer and dimmer of azure. This paper shows the use of ultra stabilized zeolite in the electrochemical field as host for molecules with nanometric dimensions. (c) 2006 Elsevier Ltd. All rights reserved.

Selective sorption of mercury(II) from aqueous solution with an organically modified clay and its electroanalytical application

The organo-clay used in this work was prepared from a Na-montmorillonite (Wyoming-USA deposit) by treatment with water solution of hexadecyltrimethylammonium cations. As organo-clays exhibit strong sorptive capabilities for organic molecules, 2-mercapto-5-amino-1,3,4-thiadiazole organofunctional groups, with potential usefulness in chemical analysis, were incorporated on its solid surface. The physically adsorbed reagent did not present any restrictions in coordinating with several metal ions on the surface. The resultant organo-clay complex exhibited strong sorptive capability for removing mercury ions from water in which other metals and ions were also present. The purpose of this work is to study the selective separation of mercury(II) from aqueous solution using the organo-clay complex, measured by batch and chromatographic column techniques, and its application as preconcentration agent in a chemically modified carbon paste electrode for determination of mercury(II) in aqueous solution.

Preparation, characterization and application of a nanostructured composite: Octakis(cyanopropyldimethylsiloxy)octasilsesquioxane

Octakis(cyanopropyldimethylsiloxy)octasilsesquioxane was prepared and characterized by C-13, Si-29 NMR (MAS), SEM, FF-IR, XRD and thermogravimetric techniques. The four groups alpha, beta, gamma, kappa (to the terminal silicon atom), associated with an acrylonitrile, were clearly seen in the C-13 NMR (alpha-CH2 at 17.9; P-CH2 at 31.3; gamma-CH, at 50.4; K-C N at 59.0 ppm). The Si-29 NMR spectrum of the final product, exhibits only Q type silicon signal, ascribed to Q(4) (-118.0 ppm). The presence of acrylonittile substituted for octameric cube confers a relative change phase and thermal stability to the material. With regard to the applications for this new material, it was intended, in this case, to react with Na-2[Fe(CN)(5)NH3] by chemical substitution. This composite was incorporated into a carbon paste electrode and the electrochemical studies were performed by cyclic voltammetry. The cyclic voltammogram of the modified graphite paste electrode, showed one redox couples with formal potential (E-1/2(ox)) = 0.24 V versus SCE. (c) 2006 Elsevier B.V. All rights reserved.

Electrochemical study of o-toluidine blue impregnated in mesoporous silica channels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)