Metal fluxes at the sediment-water interface in rivers in the Turvo/Grande drainage basin, So Paulo State, Brazil

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

Design of Gaussian basis sets to the theoretical interpretation of IR-spectrum of hexaaquachromium (III) ion, tetraoxochromium (IV) ion, and tetraoxochromium (VI) ion

The Generator Coordinate Hartree-Fock (GCHF) method is employed to design 16s, 16s10p, 24s17p13d, 25s17p13d, and 26s17p Gaussian basis sets for the H ((2)S), O ((3)P), O(2-) ((1)S), Cr(3+) ((4)F), Cr(4+) ((3)F), and Cr(6+) ((1)S) atomic species. These basis sets are then contracted to (4s) for H ((2)S), (6s4p) for O ((3)P), and O(2-) ((1)S), (986p3d) for Cr(3+) ((4)F), (10s8p3d) for Cr(4+) ((3)F), and (13s7p) for Cr(6+) (1S) by a standard procedure. For evaluation of the quality of those basis sets in molecular calculations, we have accomplished studies of total and orbital (HOMO and HOMO-1) energies at the HF-Roothaan level for the molecular species of our interest. The results obtained with the contracted basis sets are compared to the values obtained with our extended basis sets and to the standard 6-311G basis set from literature. Finally, the contracted basis sets are enriched with polarization function and then utilized in the theoretical interpretation of IR-spectrum of hexaaquachromium (III) ion, [Cr(H(2)O)(6)](3+), tetraoxochromium (IV) ion, [CrO(4)](4-), and tetraoxochromium (VI) ion, [CrO(4)](2-). The respective theoretical harmonic frequencies and IR-intensities were computed at the density functional theory (DFT) level. In the DFT calculations we employed the Becke's 1988 functional using the LYP correlation functional. The comparison between the results obtained and the corresponding experimental values indicates a very good description of the IR-spectra of the molecular ions studied, and that the GCHF method is still a legitimate alternative for selection of Gaussian basis sets. (C) 2003 Elsevier B.V. All rights reserved.

Effect of WC-10%Co-4%Cr coating on the Ti-6Al-4V alloy fatigue strength

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of Er,Cr:YSGG and Er:YAG laser irradiation on the adhesion of blood components on the root surface and on root morphology

The aim of this study was to conduct an in vitro evaluation, by scanning electron microscopy (SEM), of the adhesion of blood components on root surfaces irradiated with Er,Cr:YSGG (2.78 mu m) or Er:YAG (2.94 mu m) laser, and of the irradiation effects on root surface morphology. Sixty samples of human teeth were previously scaled with manual instruments and divided into three groups of 20 samples each: G1 (control group) - no treatment; G2 - Er,Cr:YSGG laser irradiation; G3 - Er:YAG laser irradiation. After performing these treatments, blood tissue was applied to 10 samples of each group, whereas 10 samples received no blood tissue application. After performing the laboratory treatments, the samples were observed under SEM, and the resulting photomicrographs were classified according to a blood component adhesion scoring system and root morphology. The results were analyzed statistically (Kruskall-Wallis and Mann Whitney tests, alpha = 5%). The root surfaces irradiated with Er:YAG and Er,Cr:YSGG lasers presented greater roughness than those in the control group. Regarding blood component adhesion, the results showed a lower degree of adhesion in G2 than in G1 and G3 (G1 x G2: p = 0.002; G3 x G2: p = 0.017). The Er:YAG and Er,Cr:YSGG laser treatments caused more extensive root surface changes. The Er:YAG laser treatment promoted a greater degree of blood component adhesion to root surfaces, compared to the Er,Cr:YSGG treatment.

Bond strength of adhesive restorations to Er : YAG laser-treated dentin

Background and Objective: evaluate the adhesion of adhesive restorations with and without a base of resin-modified glass-ionomer cement (RMGIC) to dentin irradiated with Er:YAG laser.Study Design/Materials and Methods: Twenty-four human molar teeth were divided into 6 groups (n=4): G1) 37% Phosphoric acid (PA) + Adhesive system (Ad) + Composite resin (CR); G2) RMGIC + CR; G3) Laser (60mJ-5Hz-20s) + PA + Ad + CR; G4) Laser (60 mJ-5 Hz-20 s) + RMGIC + CR; G5) Laser (100mJ-5Hz-20s) + PA + Ad + CR; G6) Laser (100mJ-5Hz-20s) + RMGIC + CR. Teeth were prepared, restored and cut into specimens, according to the treatment proposed and to methodology for microtensile test. Data were submitted to ANOVA and Tukey statistical tests (alpha=5%).Results:. The mean values for adhesion (MPa) and standard deviation (+/- SD) were: G1) 26.30(+/- 4.50), G2) 5.34(+/- 2.87), G3) 21.16(+/- 6.01), G4) 5.22(+/- 1.52), G5) 22.23(+/- 4.98), G6) 5.25(+/- 3.08).Conclusion: the use of Er:YAG laser did not influence on the restorations adhesion.

Application of Er:YAG and Er, Cr:YSGG lasers in cavity preparation for dental tissues: a literature review

The laser has been widely used in many specialties of dentistry and several wavelengths have been investigated as a substitute for high-speed handpiece. The purpose of this paper is to review the literature about the use of Er:YAG and Er,Cr:YSGG lasers in cavity preparation for dental tissues. Despite the differences in wavelength, pulse duration and energy, the morphological characteristics of the irradiated dentin surface with these lasers are comparable, as well as its effects as methods of dental caries prevention. Thus, Er:YAG and Er,Cr:YSGG lasers prepared cavities with similar effects on the dental tissue, however, further investigations about ideal irradiation conditions are needed for both lasers.

Estudo da resistência à corrosão de ligas Ni-Cr-Mo-Ta E Ni-Cr-Mo-W em solução NaF 0,08 mol/L, pH 4,7 para aplicações odontológicas

A large number of metal alloys are used in Dentistry for the manufacture of fixed and removable dentures. In the oral cavity, these structures are exposed to a chemically aggressive medium, like saliva and mechanical efforts, like mastication. In addition, acidic solutions containing fluoride ions are also frequently used in dental treatments to prevent dental plates and decays development. In this context, it was considered important to investigate the influence that a fourth element could exert when added to the ternary alloy Ni-Cr-Mo, largely used in Brazil. Therefore, electrochemical tests were done to evaluate the resistance to corrosion of quaternary alloy 65Ni-25Cr-5Mo-5Ta and 65Ni-25Cr-5Mo-5W in NaF solution 0,08mol / L, pH = 4.7. For greater understanding the microstructure and morphology of alloys were studied, through metallographic analysis, using optics microscopy and electron microscopy scanning. For the electrochemical tests were applied techniques traditionally used in corrosion researches, such as: potential measures in open circuit (OCP) and cyclic polarization (CP). It was found that both quaternary alloys showed very similar results. Comparing these quaternary alloys with the ternary 65Ni-25Cr-10Mo, it was found that the quaternary alloys exhibit greater resistance to corrosion, in other words, less passivation current density than the ternary alloy, showing that it is advantageous to add a fourth element in the alloy

Biosorption of Cr(III) using in natura and chemically treated tropical peats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação hemodinâmica e metabólica da cetamina e cetamina S(+) após a reposição volêmica com hidroxietilamido 130/0,4 e solução salina hipertônica 7,5%

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

Interação de genótipos de abobrinha italiana com inseticida no controle da broca das cucurbitáceas Diaphania nitidalis Cr.

A resistência de genótipos de abobrinha italiana Cucurbita pepo L. à broca das cucurbitáceas Diaphania nitidalis Cr. foi avaliada a campo. O genótipo Duda apresentou o maior número de frutos produzidos (33 frutos/parcela), enquanto Lita-186 foi o mais preferido, com a maior percentagem de frutos broqueados (3,6%). Os genótipos AG-202, Lita-186 e Duda, mais o inseticida deltametrina 25 CE foram avaliados. Duda comportou-se novamente como mais produtivo (35 frutos/parcela) e menos danificado (0,35%), confirmando os resultados obtidos no primeiro ensaio; já os genótipos AG-202 e Lita-186 revelaram-se os mais preferidos por D. nitidalis, com maiores índices de frutos danificados (2,7 e 6,3%, respectivamente).

Acute 2,4-dichlorophenoxyacetic acid intoxication in broiler chicks

The acute toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D), a herbicide, was studied in chicks dosed with 100, 300, 500, or 600 mg 2,4-D/kg BW, by the oral route. Clinical, laboratory, and histopathological methods were used as indicators of toxicity. After acute exposure, the herbicide decreased motor activity and induced muscular weakness and motor incoordination; decreased weight gain; increased serum creatine kinase (CK) and alkaline phosphatase (AP) activities and serum uric acid (UA), creatinine (CR), and total proteins (TP) levels; and did not change serum aspartate aminotransferase (AST) or alanine aminotransferase (ALT) activities. These changes were time-and dose-dependent and reversible. The LD50 (lethal dose 50%) calculated for oral 2,4-D in chicks was 420 mg/kg BW (385 to 483). Chromatographic analysis of the serum of the intoxicated chicks showed the presence of the herbicide; the amount found was dose-and time-dependent, increasing from 2 to 8 h after exposure and decreasing afterwards. Histopathological post-mortem studies conducted on intoxicated chicks showed hepatic (vacuolar degeneration of the hepatocytes), renal (tubular nephrosis), and intestinal (hemorragic) lesions. Taken together, the observed alterations mainly reflected kidney and muscle tissue damage, although hepatic toxicity may also have occurred after acute 2,4-D intoxication.

Fatigue strength of HVOF sprayed Cr(3)C(2)-25NiCr and WC-10Ni on AISI 4340 steel

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

Pulsed Nd:YAG laser seam welding of AISI 316L stainless steel thin foils

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Pulsed Nd:YAG laser welding of Ni-alloy Hastelloy C-276 foils

In this study a pulsed Nd:YAG laser was used to join Hastelloy C-276 thin foil with 100 microns thickness. Pulse energy was varied from 1.0 to 2.25 J at small increments of 0.25 J with a 4 ms pulse duration. The macro and microstructures of the welds were analyzed by optical and electronic microscopy, tensile shear test and microhardness. Sound laser welds without discontinuities were obtained with 1.5 J pulse energy. Results indicate that using a precise control of the pulse energy, and so a control of the dilution rate, it is possible to weld Hastelloy C-276 thin foil by pulsed Nd: YAG laser. (C) 2012 Published by Elsevier B. V. Selection and/or review under responsibility of Bayerisches Laserzentrum GmbH

Effect of Nd:YAG Irradiation and Fluoride Application on Dentine Resistance to Erosion in Vitro

Objective: In this paper we evaluated the effect of two fluoridated agents and Nd:YAG irradiation separately and in combination on dentine resistance to erosion. Background Data: The morphological changes in dentin induced by laser treatment may reduce the progression of erosive lesions. Due to the possibility of a synergistic effect of laser with fluoride, this study was conducted. Materials and Methods: Eighty bovine dentine samples (4 x 4 mm) were randomly divided into eight groups, according to the following treatments: G1: untreated (control); G2: acidic phosphate fluoride gel (APF 1.23%) for 4 min; G3: fluoride varnish (NaF 2.26%) for 6 h; G4: 0.5 W Nd: YAG laser (250 mu sec pulse, 10 Hz, 35 J/cm(2), 30 sec); G5: 0.75 W Nd: YAG laser (52.5 J/cm(2)); G6: 1.0 W Nd: YAG laser (70 J/cm(2)); G7: APF + 0.75 W Nd: YAG laser; and G8: NaF + 0.75 W Nd: YAG laser. After the treatments, half of each dentine surface was protected with nail varnish. The samples were stored in artificial saliva (30 mL/sample) for 24 h and submitted to four erosive 1-min cycles. Between the erosive attacks, the blocks were maintained in artificial saliva for 59 min. The erosive wear was evaluated by profilometry. Results: The mean wear (+/- SD, mu m) was: G1: 1.20 +/- 0.20; G2: 0.47 +/- 0.06; G3: 0.81 +/- 0.11; G4: 1.47 +/- 0.32; G5: 1.52 +/- 0.24; G6: 1.49 +/- 0.30; G7: 0.49 +/- 0.11; and G8: 1.06 +/- 0.31 (Tukey's test, p < 0.05). Conclusions: Laser irradiation was not able to reduce dentine erosion. However, fluoride application was able to increase the dentine's resistance to erosion, and APF showed better results than fluoride varnish.