Arc fusion of self-fluxed nickel alloys

Self-fluxed nickel alloys are usually flame fused after thermal spraying. However, due to the practical aspects of high temperatures reached during flame fusing, large structures such as the hydraulic turbines for power generation, can not be efficiently coated. An alternative is to fuse the sprayed coating with a gas tungsten electric arc. In this case, heating is much more intensive and substrate temperature during and after the fusing operation is much lower, thus reducing the possibility that any problem will occur. In this work, coatings of self-fluxed nickel alloy fused by flame and gas tungsten arc were evaluated as protection of hydraulic turbines against cavitational damage. Several tests were performed, including the ASTM ultrasonically vibration-induced cavitation, optical and scanning electronic microscopic metallography, and hardness tests. The results showed that the arc-fused coating presented better cavitation damage resistance, probably due to its finer microstructure. A field application of this new technique is also described. A self-fluxed Ni alloy was flame sprayed in critical regions of Francis-type hydraulic turbine blades and fused by a gas tungsten arc after spraying. The blades will be inspected during the next two years.

Nitric oxide release from the S-nitrosothiol zinc phthalocyanine complex by flash photolysis

The photogeneration of nitric oxide (NO) using laser flash photolysis was investigated for S-nitroso-glutathione (GSNO) and S-nitroso-N-acetylcysteine (NacySNO) at pH 6.4 (PBS/HCl) and 7.4 (PBS). Irradiation of S-nitrosothiol with light (lambda = 355 nm followed by absorption spectroscopy) resulted in the homolytic decomposition of NacySNO and GSNO to generate radicals (GS· and NacyS·) and NO. The release of NO from donor compounds measured with an ISO-Nometer apparatus was larger at pH 7.4 than pH 6.4. NacySNO was also incorporated into dipalmitoyl-phosphatidylcholine liposomes in the presence and absence of zinc phthalocyanine (ZnPC), a well-known photosensitizer useful for photodynamic therapy. Liposomes are usually used as carriers for hydrophobic compounds such as ZnPC. Inclusion of ZnPC resulted in a decrease in NO liberation in liposomal medium. However, there was a synergistic action of both photosensitizers and S-nitrosothiols resulting in the formation of other reactive species such as peroxynitrite, which is a potent oxidizing agent. These data show that NO release depends on pH and the medium, as well as on the laser energy applied to the system. Changes in the absorption spectrum were monitored as a function of light exposure.

Photophysical studies of zinc phthalocyanine and chloroaluminum phthalocyanine incorporated into liposomes in the presence of additives

The photophysical properties of zinc phthalocyanine (ZnPC) and chloroaluminum phthalocyanine (AlPHCl) incorporated into liposomes of dimyristoyl phosphatidylcholine in the presence and absence of additives such as cholesterol or cardiolipin were studied by time-resolved fluorescence, laser flash photolysis and steady-state techniques. The absorbance of the drugs changed linearly with drug concentration, at least up to 5.0 µM in homogeneous and heterogeneous media, indicating that aggregation did not occur in these media within this concentration range. The incorporation of the drugs into liposomes increases the dimerization constant by one order of magnitude (for ZnPC, 3.6 x 10(4) to 1.0 x 10(5) M-1 and for AlPHCl, 3.7 x 10(4) to 1.5 x 10(5) M-1), but this feature dose does not rule out the use of this carrier, since the incorporation of these hydrophobic drugs into liposomes permits their systemic administration. Probe location in biological membranes and predominant positions of the phthalocyanines in liposomes were inferred on the basis of their fluorescence and triplet state properties. Both phthalocyanines are preferentially distributed in the internal regions of the liposome bilayer. The additives affect the distribution of these drugs within the liposomes, a fact that controls their delivery when both are used in a biological medium, retarding their release. The addition of the additives to the liposomes increases the internalization of phthalocyanines. The interaction of the drugs with a plasma protein, bovine serum albumin, was examined quantitatively by the fluorescence technique. The results show that when the drugs were incorporated into small unilamellar liposomes, the association with albumin was enhanced when compared with organic media, a fact that should increase the selectivity of tumor targeting by these phthalocyanines (for ZnPC, 0.71 x 10(6) to 1.30 x 10(7) M-1 and for AlPHCl, 4.86 x 10(7) to 3.10 x 10(8) M-1).

Effects of nickel on the mineral composition of Fleischmann’s yeast (Saccharomyces cerevisiae)

Sugar cane juice containing 12% (w.w -1) of total reducing sugars and 0.0 to 5.0 mmol of nickel L-1, with pH ranging from 3.5 to 6.5, was inoculated with Fleischmann’s yeast (Saccharomyces cerevisiae) (10% w.w -1). Six hours after fermentation, the yeast’s cellular viability and trehalose content were evaluated. The resulting must was centrifuged and the raw yeast was analyzed by atomic absorption spectroscopy to evaluate the intracellular levels of calcium, copper, iron, magnesium, manganese, nickel, phosphorus, potassium, sulfur and zinc. The intracellular levels of iron, magnesium and calcium were affected and the yeast’s susceptibility to nickel was enhanced by the decrease in pH. The yeast’s growth was not affected by nickel at high pH, but the toxic effects of nickel were potentiated at low pH.

BASS 4: a software system for ergonomic design and evaluation of working hours

OBJECTIVE: To extend an existing computer programme for the evaluation and design of shift schedules (BASS 3) by integrating workload as well as economic aspects. METHODS: The redesigned prototype BASS 4 includes a new module with a suitable and easily applicable screening method (EBA) for the assessment of the intensity of physical, emotional and cognitive workload components and their temporal patterns. Specified criterion functions based on these ratings allow for an adjustment of shift and rest duration according to the intensity of physical and mental workload. Furthermore, with regard to interactive effects both workload and temporal conditions, e.g. time of day, are taken into account. In a second new module, important economic aspects and criteria have been implemented. Different ergonomic solutions for scheduling problems can now also be evaluated with regard to their economic costs. RESULTS: The new version of the computer programme (BASS 4) can now simultaneously take into account numerous ergonomic, legal, agreed and economic criteria for the design and evaluation of working hours. CONCLUSIONS: BASS 4 can now be used as an instrument for the design and the evaluation of working hours with regard to legal, ergonomic and economic aspects at the shop floor as well as in administrative (e.g. health and safety inspection) and research problems.

Virulence markers and antimicrobial susceptibility of bacteria of the Bacteroides fragilis group isolated from stool of children with diarrhea in São Paulo, Brazil

Bacteroides fragilis has been isolated from several human and non-human monomicrobial and mixed infections. In this study, some virulence markers and the antimicrobial susceptibility of bacteria of the B. fragilis group isolated from children's stools were evaluated. All the 64 isolates showed the following characteristics: capsulated, beta-hemolytic, hydrophilic, and serum-resistant. Only, 24 (37.5%) strains were resistant at 60ºC, for 30 min, and among them, 12 (18.75%) were resistant at 60ºC, for 60 min. Also, none strain was resistant at 100ºC. Four strains were able to hemagglutinate erythrocytes and D-mannose, D-galactose, D-arabinose, and D-xylose inhibited hemagglutination in 2 B. fragilis strains (p76a, p76b). The hemagglutination in the strain B. uniformis p3-2 was inhibited by D-xylose and D-galactose. The bft gene detection and the enterotoxin production were observed only in 13 EF-enterotoxigenic species. Fragilysin activity was confirmed on HT-29 cells. The antimicrobial determination confirmed that both imipenem and metronidazole were efficient against B. fragilis species; all the strains were resistant to lead and nickel. Plasmids of 2.9, 4.4, 4.8, and 8.9 kb were observed in 6 tested strains. These results show the values of the species identification from clinical infections, as well as of the periodic evaluation of the resistance patterns of the B. fragilis group at Brazilian medical institutions.

Survey of antimicrobial susceptibility patterns of the bacteria of the Bacteroides fragilis group isolated from the intestinal tract of children

The bacteria of the Bacteroides fragilis group are considered important clinical pathogens and they are the most common anaerobes isolated from human endogenous infections. In this study, the susceptibility patterns to antibiotics and metals of 114 species of the B. fragilis group isolated from children with and without diarrhea were determined. Susceptibility was assayed by using an agar dilution method with Wilkins-Chalgren agar. All B. fragilis strains were resistant to lead and nickel, but susceptible to metronidazole and imipenem. beta-lactamase production was detected by using biological and nitrocefin methods, respectively, in 50% and 90.6% of the isolates of children with diarrhea and in 60% and 90% of the isolates of children without diarrhea. Our results show an increase of antibiotics and metals resistance in this microbial group, and a periodic evaluation of the antimicrobial susceptibility is needed. In Brazil, the contamination for antibiotics or metal ions is often observed, and it is suggested an increase the antimicrobial resistance surveillance of this microbial group, mainly those isolated from children's diarrhea.

Characterization and nutrient release from silicate rocks and influence on chemical changes in soil

The expansion of Brazilian agriculture has led to a heavy dependence on imported fertilizers to ensure the supply of the growing food demand. This fact has contributed to a growing interest in alternative nutrient sources, such as ground silicate rocks. It is necessary, however, to know the potential of nutrient release and changes these materials can cause in soils. The purpose of this study was to characterize six silicate rocks and evaluate their effects on the chemical properties of treated soil, assessed by chemical extractants after greenhouse incubation. The experimental design consisted of completely randomized plots, in a 3 x 6 factorial scheme, with four replications. The factors were potassium levels (0-control: without silicate rock application; 200; 400; 600 kg ha-1 of K2O), supplied as six silicate rock types (breccia, biotite schist, ultramafic rock, phlogopite schist and two types of mining waste). The chemical, physical and mineralogical properties of the alternative rock fertilizers were characterized. Treatments were applied to a dystrophic Red-Yellow Oxisol (Ferralsol), which was incubated for 100 days, at 70 % (w/w) moisture in 3.7 kg/pots. The soil was evaluated for pH; calcium and magnesium were extracted with KCl 1 mol L-1; potassium, phosphorus and sodium by Mehlich 1; nickel, copper and zinc with DTPA; and the saturation of the cation exchange capacity was calculated for aluminum, calcium, magnesium, potassium, and sodium, and overall base saturation. The alternative fertilizers affected soil chemical properties. Ultramafic rock and Chapada mining byproduct (CMB) were the silicate rocks that most influenced soil pH, while the mining byproduct (MB) led to high K levels. Zinc availability was highest in the treatments with mining byproduct and Cu in soil fertilized with Chapada and mining byproduct.

Production of polyclonal antisera using recombinant coat proteins of Grapevine leafroll-associated virus 2 and Grapevine virus B

The objective of this work was to produce and characterize specific antisera against Brazilian isolates of Grapevine leafroll-associated virus 2 (GLRaV-2) and Grapevine virus B (GVB), developed from expressed coat proteins (CPs) in Escherichia coli, and to test their possible use for the detection of these two viruses in diseased grapevines. The coat protein (CP) genes were RT-PCR-amplified, cloned and sequenced. The CP genes were subsequently subcloned, and the recombinant plasmids were used to transform E. coli cells and express the coat proteins. The recombinant coat proteins were purified, and their identities were confirmed by SDS-PAGE and Western blot and used for rabbit immunizations. Antisera raised against these proteins were able to recognize the corresponding recombinant proteins in Western blots and to detect GLRaV-2 and GVB in infected grapevine tissues, by indirect ELISA, discriminating healthy and infected grapevines with absorbances (A405) of 0.08/1.15 and 0.12/1.30, respectively. Expressing CP genes can yield high amount of viral protein with high antigenicity, and GLRaV-2 and GVB antisera obtained in this study can allow reliable virus disease diagnosis.

Desempenho agronômico de videiras com e sem sintomas de viroses, e comparação molecular de isolados virais

Resumo: O objetivo deste trabalho foi avaliar os efeitos de viroses em videiras sintomáticas e assintomáticas sobre as variáveis agronômicas relacionadas ao vigor das plantas e à qualidade enológica da uva, e comparar os isolados virais obtidos nessas duas condições. Realizaram-se dois experimentos com quatro cultivares. Todas as plantas foram indexadas, por meio da reação em cadeia da polimerase via transcrição reversa (RT-PCR) em tempo real, quanto à provável ocorrência dos seguintes vírus: Grapevine virus A (GVA), Grapevine virus B (GVB), Grapevine virus D (GVD), Grapevine leafroll-associated virus (GLRaV-1 ao -4, GLRaV-4 estirpe 5), Grapevine rupestris stem pitting-associated virus (GRSPaV) e Grapevine fleck virus (GFkV). As variáveis avaliadas foram: número de gemas brotadas e não brotadas, número de ramos com ou sem cachos, número total de gemas, número de cachos, massa de cachos frescos, massa total de bagas, massa do engaço, número de bagas por cacho, massa média de baga, sólidos solúveis totais, acidez total titulável, pH, massa de ramos podados ou diâmetros do tronco do porta-enxerto e da copa. Os efeitos negativos foram mais pronunciados nas plantas com sintomas de viroses; no entanto, constatou-se frequentemente que plantas sem sintomas também estavam infectadas. A análise molecular de GRSPaV, GVA e GLRaV-2, isolados de plantas sintomáticas e assintomáticas, resultou em alta percentagem de identidade de nucleotídeos entre isolados homólogos.

Desenvolvimento de um processo de lixiviação dos concentrados de manganês em sais fundidos

The NaCl- KCl system as fused-salt solvent for leaching has shown to have some advantages over traditional solvents. In this work the solubility of copper, nickel and cobalt oxide in this system, as impurities in manganese concentrate, was studied. The euthetic mixture of NaCl - KCl at 700ºC was used at several fusion times and the dissolved metals were determined by Atomic Absorption Spectrometry. The results have shown that in these conditions only copper was solubilized.

Alteração do comportamento eletroquímico do eletrodo de níquel, em ácido sulfúrico diluído, sob diferentes condições de iluminação

In this paper is presented electrochemical evidences of the influence of the light on the electrochemical behavior of nickel electrode in diluted sulfuric acid. The current densities related with the electrooxidation of the metal decreases when the electrode is under illumination. The corrosion potential, Ecorr , shift to a more positive value in this condition. This effect was observed with polychromatic light and with different wavelength glass filters such as 700 nm and 520 nm. It was observed that increasing the temperature of the solution, the current densities related with cathodic and anodic processes, increases instead of decreases. The activation energy related with the electrooxidation of the electrode was higher under illumination than in the dark. It is suggested that this behavior may be related or with a photo-inhibition effect either with dessorption of adsorbed water involved in the electrooxidation mechanism.

Determinação simultânea de cobalto e níquel

The simultaneous determination of cobalt and nickel is a classical analytical problem. A great number of reagents associated with several techniques of analysis have been applied to achieve this determination. In this review 117 references, which appeared between 1996-1980, are described and classified according to the technique applied.

Processo alternativo para remoção de cobre (II) e níquel (II) de soluções aquosas utilizando cápsulas de quitosana - Álcool Polivinílico

Capsules were prepared from chitosan (QTS)-poly(vinyl alcohol) (PVA) blend by saline coacervation and then by formalization. A adsorbent based on chitosan, insoluble on acid solution, was obtained. The morphology, average diameters of QTS/PVA capsules and their pores were studied by using scanning electron microscopy. The entrapment-adsorption of dimethylglioxime and ethylenediaminetetracetate by the capsules were studied. The removal of the ion nickel (II) and copper (II), was more effective than by using unloaded capsules.

Implementação de um sistema de eletroforese capilar com detecção de fluorescência induzida por laser

A capillary electrophoresis system using laser induced fluorescence detection is described. A Raman system equipped with a microscope has been used to focus the laser beam on the capillary giving a lateral resolution of 1.5 mm. The fluorescence signal of the analyte (ZnPcTS - tetrasulfonated zinc-phthalocyanine) was collected by the microscope objectives and analysed by a monochromator with confocal characteristics equipped with a CCD detector. Electropherograms obtained with this system were compared to those obtained on a commercial instrument, showing that the described system presents a lower detection limit and better resolution.