REDUCTION OF TODA LATTICE HIERARCHY TO GENERALIZED KDV HIERARCHIES AND THE 2-MATRIX MODEL

Toda lattice hierarchy and the associated matrix formulation of the 2M-boson KP hierarchies provide a framework for the Drinfeld-Sokolov reduction scheme realized through Hamiltonian action within the second KP Poisson bracket. By working with free currents, which Abelianize the second KP Hamiltonian structure, we are able to obtain a unified formalism for the reduced SL(M + 1, M - k) KdV hierarchies interpolating between the ordinary KP and KdV hierarchies. The corresponding Lax operators are given as superdeterminants of graded SL(M + 1, M - k) matrices in the diagonal gauge and we describe their bracket structure and field content. In particular, we provide explicit free field representations of the associated W(M, M - k) Poisson bracket algebras generalising the familiar nonlinear W-M+1 algebra. Discrete Backlund transformations for SL(M + 1, M - k) KdV are generated naturally from lattice translations in the underlying Toda-like hierarchy. As an application we demonstrate the equivalence of the two-matrix string model to the SL(M + 1, 1) KdV hierarchy.

Spectroscopic studies of the Eu3+ and Er3+ ions in the fluorozirconate LaZr2F11 matrix

An investigation by optical spectroscopy of the Eu3 + and Er3 + active ions in the crystallized fluorozirconate matrix LaZr2F11 is presented. The D-5(1) --> F-7(0-5) emission lines of Eu3 + are used to extract the F-7(0-5) energy scheme and the observed extinctions permit the deduction of irreducible representations (IRREPS) associated with corresponding sub-levels in the D-2 symmetry. The crystal field analysis was carried out on a 387 x 387 basis set, comprising the F-7, D-5(1,2,3) F-5(1,2), (5)G(1,2,3) and P-3(1,2,3,4,5,6) terms of the Eu-3 (+) 4f(6) configuration. The deviation and rms are 6.8 and 7.9 cm (-1), respectively for 38 levels and ten parameters. The experimental crystal field parameters are in good agreement with the ab-initio ones. Moreover, the relative intensities of the D-5(0) --> F-7(2,3,4) emissions are well reproduced by an 'ab-initio' calculation, except for three lines. The Er3 + ions introduced in LaZr2F11, microcrystals also lie in an unique crystallographic site. A total of 31 energy levels were recorded and the crystal field analysis led to 6.6 and 7.8 cm (-1) for the deviation and rms, respectively, for nine variable parameters taken into account. The experimental CF parameters for Er3 + and Eu3 + are very similar, which seems to show that the host lattice contracts around the smaller Er3 + ion. The informations given by both Eu3 + and Eu3 + optical probes in LaZr2F11 are very consistent with the structure previously determined for the isotypic PrZr2F11 fluoride. (C) 2000 Elsevier B.V. B.V. All rights reserved.

Benzoate ion determination in beverages by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely. Pt\Hg\Hg-2(Bzt)(2)\graphite, where Bzt stands for benzoate ion. are described. This electrode responds to Bzt with sensitivity of 57.7 +/- 1.0 mV/decade over the range 5 x 10(-4)-1 x 10(-1) mol l(-1) at pH 6.0-8.0 with a detection limit of 1.6 x 10(-4) mol l(-1). The electrode shows easy construction, fast response rime (between 10-30 s), low-cost, acid excellent response stability (lifetime > 6 months, in continuous use), the proposed sensor displayed good selectivity for benzoate in the presence of several carboxylate and inorganic anions. It was used to determine benzoate in various beverages by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by the official AOAC spectrophotometric method and by a HPLC procedure as well. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Luminescence of Eu(III) beta-diketone complex supported on functionalized macroporous silica matrix

This work reports on the photoluminescent properties of the complex diequatris(thenoyltrifluoroacetonate) europium(III), which was adsorbed or supported on tubes of modified surface silica matrix. The luminescence data and the experimental intensity parameter results evidence the existence of high interactions between the complex [Eu(tta)(3)(H2O)(2)] and the modified surface matrix. The anchored complex on macroporous silica shows higher intensity parameter values suggesting that the Eu-0 bond becomes more covalent than the adsorbed one. Therefore, the hypersensitive character of the D-5(0) --> F-7(2) transition increases evidencing a high contribution of the dynamic coupling mechanism possibly due to highly polarizable chemical environments occupied by europium(III) ion. The lifetimes of the complex on silica matrices were measured. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

p-Aminobenzoate ion determination in pharmaceutical formulations by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely, Pt\Hg\Hg-2(PABzt)(2)\ graphite, where PABzt stands for p-aminobenzoate ion, are described. This electrode responds to PABzt with sensivity of (58.1 +/- 1.0) mV per decade over the range 1.0 x 10(-4) to 1.0 x 10(-1) mol l(-1) at pH 6.5-8.0 and a detection limit of 3.2 x 10(-5) mol l(-1). The electrode shows easy construction, fast response time (within 10-30 s), low-cost, and excellent response stability (lifetime greater than 6 months, in continuous use). The proposed sensor displayed good selectivity for p-aminobenzoate in the presence of several substances, especially, concerning carboxylate and inorganic anions. It was used to determine p-aminobenzoate in pharmaceutical formulations by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by an HPLC procedure. (C) 2004 Elsevier B.V. All rights reserved.

Reactionary dentinogenesis after applying restorative materials and bioactive dentin matrix molecules as liners in deep cavities prepared in nonhuman primate teeth

Objective: the aim of this in vivo study was to evaluate the response of the pulp-dentin complex following application of resin-modified glass-ionomer cement, calcium hydroxide hard-setting cement and EDTA-soluble preparation of dentine matrix proteins (ESDP) in deep cavities prepared in non-human primate teeth. Methods: Eighteen deep Class V buccal cavities were prepared in premolars of four capuccin monkeys. In Groups 1 and 2, the cavity floor was lined with ESDP or a resin-modified glass-ionomer cement (Vitrebond - 3M ESPE), respectively. In Group 3 (control), the cavity was lined with a hard setting calcium hydroxide cement (Dycal - Dentsply). The cavities were subsequently filled with amalgam. After 6 months, the animals were sacrificed and the teeth were prepared for microscopic assessment. Six-micron thick serial sections were stained with H/E, Masson's trichrome and Brown & Brenn techniques. Results: No inflammatory pulpal response was observed for all experimental and control Groups. However, the amount of reactionary dentin deposition differed between groups in the rank order ESDP (Group 1) > calcium hydroxide (Group 3) > resin-modified glass-ionomer (Group 2). These differences were statistically significant. Conclusions: All materials were biocompatible when applied in deep cavities. ESDP stimulated higher deposition of reactionary dentin matrix than Vitrebond and Dycal.

Mixed micelles of the anionic surfactant sodium dodecyl sulfate and the nonionic pentaethylene glycol mono-n-dodecyl ether in solution

Dynamic light scattering, surface tension, and clouding temperature have been monitored to elucidate the solution properties of mixed micelles formed between the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant pentaethylene glycol mono-n-dodecyl ether (C12E5) over a wide range of surfactant concentration and temperature. Addition of 0.1 M NaCl shifts the relaxational modes to higher frequency and lowers the clouding temperature (T-c) of the nonionic surfactant solution by about 1 degrees C compared to the salt-free system. T-c for the mixed surfactant solutions is higher than that of the binary C12E5 solutions and depends sensitively on the concentration of the two surfactants but increases only slightly when the total surfactant concentration is increased at a given molar C12E5/SDS concentration ratio. With C12E5/SDS = 5.7, for example, T-c is 46.0 and 47.5 degrees C, respectively, at 5 and 70 mM of C12E5 the mixed solutions are homogeneous and stable and contain nonspherical micelles, which are close to monodisperse over a range of surfactant concentrations and temperature. The mixed system has a lower Krafft point than binary SDS solutions and shows an approximately ideal behavior in contrast to the binary C12E5 solution. The hydrodynamic radius (RH) of the mixed micelle increases with temperature as do C12E5 micelles in the binary solutions and also with increasing C12E5/SDS ratio. At 25 degrees C, the critical micelle concentration of the mixed solution lies between those of the individual surfactants and decreases as the C12E5/SDS ratio is increased.

Molecular dynamics simulation on devitrification: Isothermal devitrification and thermodynamics of PbF2 glasses

The vitrification and devitrification features of lead fluoride are investigated by means of molecular dynamic simulations. The influence of heating rate on the devitrification temperature as well as the dependence of the glass properties on its thermal history, i.e., the cooling rate employed, is identified. As expected, different glasses are obtained when the cooling rates differ. Diffusion coefficient analysis during heating of glass and crystal, indicates that the presence of defects on the glassy matrix favors the transition processes from the ionic to a superionic state, with high mobility of fluorine atoms, responsible for the high anionic conduction of lead fluoride. Nonisothermal and isothermal devitrification processes are simulated in glasses obtained at different cooling rates and structural organizations occurring during the heat treatments are clearly observed. When a fast cooling rate is employed during the glass formation, the devitrification of a single crystal (limited by the cell dimensions) is observed, while the glass obtained with slower cooling rate, allowing relaxations and organization of various regions on the glass bulk during the cooling process, devitrifies in more than one crystalline plane. (C) 2004 American Institute of Physics.

Genetic analysis of phosphoprotein and matrix protein of rabies viruses isolated in Brazil

To investigate the genetic characteristics of phosphoprotein (P) and matrix protein (M) genes of variable rabies virus (RV) prevalent in Brazil, the authors genetically characterized the P and M genes from 30 Brazilian RV field isolates. Phylogenetic analysis based on the P and M genes revealed the presence of six RV variants that consisted primarily of three insectivorous bats, the vampire bat, dog and fox in Brazil. Specific amino acid substitutions corresponding to these phylogenetic lineages were observed, with ASP(42) and GlU(62) in the P protein found to be characteristic of Brazilian chiroptera- and carnivora-related RVs, respectively. Amino acid sequence motifs predicted to associate with a viral function in the P and M proteins were conserved among Brazilian RV variants.

Evaluation of anionic collagen membranes in the treatment of class II furcation lesions: an histometric analysis in dogs

This study aims to evaluate the effect of using anionic collagen membranes in guided tissue regeneration treatment of Class II furcation lesions in dogs. The defects were created in the buccal furcation of 16 mandibular premolars of four dogs. After 56 days without plaque control, the sites were scaled and divided into two groups according to the treatment applied: control sites, open flap debridement; and test sites, guided tissue regeneration treatment. The animals were killed after 3 months. Histological and histometrical analyses showed that the collagen membrane was better than open flap debridement in terms of newly formed cementum and epithelial migration prevention. It provided effective blockade of epithelial tissue and promoted regeneration of lost periodontal tissues, suggesting that the membrane warrants further study. (C) 1997 Elsevier B.V. Limited. All rights reserved.

Effect of a pilot washing system on dicofol levels in orange matrix

An efficient analytical method is described for the analysis of dicofol residues in pulp and orange peel. Samples are mixed with Celite and transferred to chromatographic columns prepacked with silica gel. Dicofol is eluted with ethyl acetate, and the extracts are analyzed by gas chromatography with electron capture detection. Mean recoveries for dicofol at levels of 0.5, 2.0, 5.0, and 10 mg/kg ranged from 87 to 95% with relative standard deviation values between 2.6 and 9.0%. To investigate the effect of a pilot washing system on dicofol residues in oranges, the analytical procedure was applied to samples submitted to different treatments with commercial formulations under field and laboratory conditions. The orange samples with and without washing were analyzed in duplicate, and the results indicated that washing under the described conditions did not allow a complete removal of dicofol residues from orange peel.

Glyceraldehyde-3-phosphate dehydrogenase of Paracoccidioides brasiliensis is a cell surface protein involved in fungal adhesion to extracellular matrix proteins and interaction with cells

The pathogenic fungus Paracoccidioides brasiliensis causes paracoccidioidomycosis, a pulmonary mycosis acquired by inhalation of fungal airborne propagules, which may disseminate to several organs and tissues, leading to a severe form of the disease. Adhesion to and invasion of host cells are essential steps involved in the infection and dissemination of pathogens. Furthermore, pathogens use their surface molecules to bind to host extracellular matrix components to establish infection. Here, we report the characterization of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of P. brasiliensis as an adhesin, which can be related to fungus adhesion and invasion. The P. brasiliensis GAPDH was overexpressed in Escherichia coli, and polyclonal antibody against this protein was obtained. By immunoelectron microscopy and Western blot analysis, GAPDH was detected in the cytoplasm and the cell wall of the yeast phase of P. brasiliensis. The recombinant GAPDH was found to bind to fibronectin, laminin, and type I collagen in ligand far-Western blot assays. of special note, the treatment of P. brasiliensis yeast cells with anti-GAPDH polyclonal antibody and the incubation of pneumocytes with the recombinant protein promoted inhibition of adherence and internalization of P. brasiliensis to those in vitro-cultured cells. These observations indicate that the cell wall-associated form of the GAPDH in P. brasiliensis could be involved in mediating binding of fungal cells to fibronectin, type I collagen, and laminin, thus contributing to the adhesion of the microorganism to host tissues and to the dissemination of infection.