Influence of thermal treatments in the corrosion behaviour of HVOF Cr 3C2-NiCr coatings

Thermal spray coatings as Cr3C2-NiCr obtained by high velocity oxy-fuel spraying (HVOF) are mainly applied due to their behaviour against aggressive erosive-abrasive and corrosive atmospheres and their thermal stability at high temperatures [1]. In order to increase the corrosion protection that it offers to the substrate trying to close the interconnected pores, it is possible to apply a thermal treatment with the gun during the spraying of the coating. This treatment could be applied in different ways. One of these ways consists of spraying only a few layers of coating followed by thermal treatment and finally the spray of the rest of layers. This thermal treatment on spraying is studied related to the corrosion properties of the system. The study comprises the electrochemical characterisation of the system by open circuit potential (OC), polarisation resistance (Rp), cyclic voltammetry (CV) and impedance spectroscopy measurements (EIS). Optical and scanning electron microscopy characterisation (OM and SEM) of the top and cross-section of the system has been used in order to justify the electrochemical results.

Efeito do extrato aquoso de sete-sangrias [Cuphea mesostemon (Koehne) Lourt] sobre o fluxo de água, medido em bexiga urinária de sapo in vitro

The Cuphea mesostemon specie, known as sete-sangrias, is widely used as a diuretic substance in popular medicine. As the toad urinary bladder is an epithelium analogous to the distal nephron of mammals, it is used in order to study the transport water and electrolytes in many laboratories. This preparation permits excellent observation in water flow, from the urinary bladder lumen to the external side or the serosal one (water re-absorption), by means of gravimetrical measures. In the present work the hydrosmotic effect of aqueous extract (AE) of sete-sangrias leaf was studied. A 20% solution was added to the serosal side (S) of the bladder preparation, and the water flow was measured every 15 minutes after that. The results showed that 4mL of AE in the S side, increased the JH20 in a significant manner (p<0,05). This effect had a dose - response shape, with the volumes of 0,2mL, 0,4mL and 0,8mL of AE in the S bath. The hydro-osmotic effect of the anti-diuretic hormone (ADH) was studied as well and a significant stimulation (p<0,05) in the JH2O was observed with the magnitude of 150%. The AE effect was similar to the ADH one, and was not antagonized by this hormone. We concluded that Cuphea possesses an anti-diuretic activity similar to that presented by ADH, in toad urinary bladder, in vitro.

Dietary electrolyte balance for broiler chickens under moderately high ambient temperatures and relative humidities

Cobb male broiler chicks (1,000) on new litter were used to evaluate effects of dietary electrolyte balance [DEB; Na+K-Cl, milliequivalents (mEq) per kilogram] under tropical summer conditions. Corn-soybean meal-based mash diets had salt (NaCl) alone or in combination with one or more supplements: sodium bicarbonate (NaHCO3), ammonium chloride (NH4Cl), or potassium bicarbonate (KHCO3). A completely randomized design, with five starter and grower feed treatments (control: 145, then 130 mEq/kg; or 0, 120, 240, or 360 mEq/kg throughout) and four replicate pens (1.5 x 3.2 m) per treatment (50 chicks per pen), was used. Diets were analyzed for Na, K, and Cl for confirmation. There were no significant (P < 0.05) effects of treatments on mortality or processing parameters. Water intake increased linearly with increasing DEB, giving higher litter moistures and lower rectal temperatures. Blood HCO3 and pH increased with the highest DEB (360 mEq/kg) causing respiratory alkalosis. The DEB of 240 mEg/kg gave best weight gain and feed conversion ratio, and ideal DEB predicted by regression analyses were 186 and 197 mEq/kg from 0 to 21 d of age and 236 and 207 mEq/kg of feed from 0 to 42 d, respectively. These DEB corresponded to estimated (interpolated) values in predicted optimal 186 to 197 mEq/kg starter of Na 0.38 to 0.40% and Cl 0.405 to 0.39% (K = 0.52%), in 207 to 236 mEq/kg starter, Na 0.409 to 0.445% and Cl 0.326 to 0.372% Cl (K = 0.52%), and in grower Na 0.41 to 0.445%, Cl 0.315 to 0.267% (K = 0.47%).

Dietary electrolyte balance for broiler chickens exposed to thermoneutral or heat-stress environments

Ross male broiler chicks (n = 480) on new litter were used in a randomized block design with two blocks (environmental rooms) and four treatments having four replicate pens (1.0 × 2.5 m; 15 chicks) each to evaluate dietary electrolyte balance (DEB; P < 0.05). Two rooms were 1) thermoneutral (Weeks 1 through 6, with decreasing maximum from 32 to 25°C and minimum from 28 to 19°C; relative humidity 49 to 58%) and 2) cyclic daily heat stress (Weeks 1 and 2, thermoneutral; Weeks 2 through 6, maximum temperatures 35, 35, 33, and 33°C, respectively; and minimum temperatures 23, 20, 19, and 19°C, respectively; relative humidity 51 to 54%). The DEB treatments (0, 140, 240, or 340 mEq Na + K - Cl/kg) had NaHCO3 plus NH4Cl, or KHCO3, or both added to corn-soybean meal mash basal diets with 0.30% salt (NaCl). In the thermoneutral room, DEB 240 increased 42-d weight gain and 44-d lymphocyte percentage and decreased heterophil percentage and heterophil to lymphocyte ratio compared to the DEB 40 treatment. The DEB 240 diets had 0.35 and 0.35% Na and 0.37% and 0.29% Cl in starter (0.75% K) and grower (0.67% K) diets, respectively. No DEB treatment differences were found in the heat stress room. For combined rooms, 42-d feed intake was higher for DEB 240 than for DEB 40. The 21-d weight gain was higher for DEB 240 than for DEB 40 or 140; and 21-d feed/gain was lower for DEB 40 than for DEB 340. The predicted maximum point of inflection for 21- and 42-d weight gains were DEB 250 and 201, with highest 42-d feed intake at 220.

Photoelectrocatalytic degradation of Remazol Brilliant Orange 3R on titanium dioxide thin-film electrodes

Degradation of reactive dye Remazol Brilliant Orange 3R (RBO) has been performed using photoeletrocatalysis. A biased potential is applied across a titanium dioxide thin-film photoelectrode illuminated by UV light. It is suggested that charges photogenerated at the electrode surface give rise to chlorine generation and powerful oxidants (OH) that causes the dye solution to decolorize. Rate constants calculated from color decay versus time reveal a first-order reaction up to 5.0×10-5 mol l-1 in dye concentration. The best experimental conditions were found to be pH 6.0 and 1.0 mol l-1 NaCl when the photoelectrode was biased at +1V (versus SCE). Almost complete mineralization of the dye content (70% TOC reduction) was achieved in a 3-h period using these conditions. Effects of other electrolytes, dye concentration and applied potentials also have been investigated and are discussed. © 2003 Elsevier Science B.V. All rights reserved.

Células sangüíneas, eletrólitos séricos, relação hepato e esplenossomáca de carpa-comum, Cyprinus carpio (Cyprinidae) na primeira maturação gonadal

This research studied the condition (Kn) relative factor, the hepatosomatic (HSR), the splenosomatic (SSR) relation, the erythrocytes, thrombocytes and leukocytes number, the glicogen locality by PAS method in thrombocytes and leucocytes and the total protein and electrolytes serices levels in both Cyprinus carpio L. sex. The female Kn showed higher value than the males. The female HSR average values were lower than the ones observed in males, while the leukocytes, lymphocytes and neutrophils percentage number were the highest. However, the males magnesium and choride serices levels were higher than the females. The HRS average values, hematocrit, haemoglobin concentration, average corspucular volume (ACV), average corpuscular haemoglobin concentration (ACHC), erythocytes number, trombocytes, monocytes, oesinophils, positive PAS leukocyte granular (PAS-LG), and total protein, sodium, potassium and calcium serices levels did not show significant statistics difference (p> 0.05) between males and females. The PAS method showed glicogen granules into the thronbocytes, eosinophils and neutrophils cytoplasm. Nevertheless, in the PAS-LG cytoplasm, neutral glicoprotein granules were also observed. Monocytes and lynfocytes showed negative reaction to PAS. In the teleosts, the gonodas matureness presents higher relation with the factor of condition. During the reprodution period it is unlikely to find the sexual effects isolated in the hemogram, because most of the time that is not the only factor to cause dimorphism.

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram)

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and waterrfeed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32°C in 30 min, 32 to 36°C in 30 min, 36 to 37°C in 15 min, and 37 to 41°C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 ± 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB O decreased blood Na and K, and DEB O and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB O and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

An ellipsometric study of manganese oxide films: In situ characterization of the deposition and electroreduction of MnO2

The electrodeposition of manganese oxide films onto a platinum substrate was investigated by means of in situ ellipsometry. In the thickness range from 0 to 150 nm, the anodic oxide behaves as an Isotropic single layer with optical constants that are independent of thickness. Deviations at higher thickness are explained in terms of anisotropic properties of the film. The electroreduction of thin films (up to ca. 150 nm) in an alkaline electrolyte leads to a decrease in both the refractive index and the extinction coefficient and is accompanied by a thickness increase of ca. 10%. The Mn(IV) to Mn(III) conversion takes place from the oxide/electrolyte interface inwards. © 2004 The Electrochemical Society. All rights reserved.

Lack of inhibitory effect of zinc on prolactin secretion induced by cimetidine

The dopaminergic, serotoninergic and GABA-ergic systems are closely involved in PRL secretion, as well as thyrotropin-releasing hormone. There is some evidence that zinc interacts with some of these neuroamines and neuropeptides. The histamine H2-receptor cimetidine stimulates PRL secretion rapidly following an intravenous injection in man. In this sense, we investigated probable inhibitory effect of zinc on prolactin secretion following cimetidine injection (300 mg). Therefore, we studied five healthy adult men, before and after oral zinc administration (25 mg elemental zinc) during three consecutive months. The results did not demonstrate any inhibitory effect of zinc on prolactin secretion. So, we originally concluded that zinc did not interact with dopamine, serotonine, gamma-aminobutyric acid and the thyrotropin-releasing hormone in humans. In addition, the intravenous administration of cimetidine did not change the serum zinc profile. © 2005 Dustri-Vertag Dr. K. Feistle.

Efeitos do extrato aquoso de cebola (Allium cepa L.) sobre a função renal e a pressão arterial em ratos Wistar

The vegetal species, Allium cepa, known as onion, is widely used in the folk medicine as diuretic, besides it has been used on the bronchitis, cough, cardiovascular diseases and hypertension treatment. In this study we evaluate the onion aqueous extract (AE) effect on water flow and electrolytes in anesthetized Wistar rats, besides we also evaluate arterial pressure alterations. Two groups were studied: Group 1 (control) - oral tratment with 1.0 mL of distilled water, and Group 2 (experimental) - oral treatment with 1.0 mL of AE 20%. The rats were anesthetized and we canulate the trachea, left carotide artery (for arterial pressure measurement and blood collecting), jugular vein (to execute inulin perfusion - to register glomerular filtration), and urinary bladder (to collect urine). The Group 1 results had shown that the animals had not presented significant alterations (p>0.05) in the analyzed parameters. The animals of Group 2 had a significant reduction (p<0.05) in the arterial pressure (22.0%). However, there were not significant alterations in renal parameters (p>0.05). These results show that the treatment with the AE lead a hypotensor effect in anesthetized Wistar rats, but not followed by renal parameters alterations.

Zinc does not inhibit prolactin secretion during insulin-induced hypoglycemia in normal men

Zinc (Zn ++) has been shown as an important physiological inhibitor of pituitary PRL release, and Zn ++ and PRL could be involved in a negative feedback regulatory loop. However, this inhibitory effect has not been detected in humans with regard to thyrotropin releasing hormone (TRH), dopamine (DA) and histamine (HA) neurotransmitters. In order to investigate this topic, Zn ++ was acutely and chronically administered to five healthy men to observe the probable inhibitory effect on PRL release during insulin-induced hypoglycemia. The positive PRL response to hypoglycemia has generally been considered to be mediated via the hypothalamus by adrenergic, serotoninergic, histaminergic, opioid-peptidergic and TRH neurotransmitters. The results showed that Zn ++ was not able to inhibit the PRL release during insulin-induced hypoglycemia. Under these conditions, Zn ++ does not block hypothalamic neurotransmitters stimulated by hypoglycemia, thus excluding its clinical application in human beings. On the other hand, the effect of acute stress, such as hypoglycemia, on the serum Zn ++ profile was not observed. ©2006 Dustri-Verlag Dr. K. Feistle.

Parâmetros fisiológicos do desempenho de cavalos de alta performance hidratados voluntariamente com água ou solução isotônica contendo carboidrato

During eight weeks, in summer, four endurance trained high performance horses were worked in resistence exercise, recieving two different types of hydratatio, water or an isotonic solution containing carbohydrates, with the objective to compare their performance physiological parameters. Only the RT (rectal temperature), HR (heart rate), RR (respiratory rate), weight, total protein, glucose, the electrolytes K, Ca and the muscular enzyme CK presented distance effect. The others parameters evaluated, there weren't any identified effects of treatment and of the interaction between distance and treatments, with a significancy level of 5%, and it was concluded that the isotonic solution containing carbohydrate didn't have any significant influence on the animal's performance when compared to water.

Voltammetry of mercury (II) based on an organo-clay modified graphite electrode

Organo-clay complex of ligand-hexadecyltrimethylammonium with montmorillonite was made for the purpose of application as a preconcentration agent in a chemically modified carbon paste electrode for determination of mercury (II) in aqueous solution. It was found out that the adsorption of Hg(II) by organo-clay complex is independent of the pH of the solution. It was also found out that the adsorption of the remaining metals Cd(II), Ps(II), Cu(II), Zn(II), and Ni(II) was dependent on the changes in pH solutions and increased when it varies from 1 to 8. The resultant material was characterized by cyclic and differential pulse anodic voltammetry using a modified graphite paste electrode in different supporting electrolytes. The mercury response was evaluated with respect to pH, electrode composition, preconcentration time, mercury concentration, possible interferences and other variables.

Formation of silver chloride nanocrystals as a corrosion product of silver in H2SO4 solution

The purpose of this study is to characterize the corrosion product on the surface of silver, employing H2SO4 (0.5M) as electrolyte. The electrochemical parameters, Ecor, Icor, V cor and Rp were obtained after analyzing the potentiodynamic polarization curve in which two peaks were observed. The smallest (passive region) is attributed to the Cl- traces from the reference electrode, with micro-cracks. The second peak (in the transpassivation region) corresponds to the polarization curve of silver in H2SO 4 without contaminants. SEM images and EDS analysis reveal images of a surface layer on silver, consisting of structures containing sulfur, oxygen, silver and chloride, as the corrosion product. On this layer silver sulfate crystals were observed, which occurs during the formation of silver chloride nanocrystals with different morphologies, when chloride ions were added to the electrolyte medium. ©The Electrochemical Society.

Tetragonal to monoclinic phase transition observed during Zr anodisation

Plasma electrolytic oxidation (PEO) is a coating procedure that utilises anodic oxidation in aqueous electrolytes above the dielectric breakdown voltage to produce oxide coatings that have specific properties. These conditions facilitate oxide formation under localised high temperatures and pressures that originate from short-lived microdischarges at sites over the metal surface and have fast oxide volume expansion. Anodic ZrO2 films were prepared by subjecting metallic zirconium to PEO in acid solutions (H2C 2O4 and H3PO4) using a galvanostatic DC regime. The ZrO2 microstructure was investigated in films that were prepared at different charge densities. During the anodic breakdown, an important change in the amplitude of the voltage oscillations at a specific charge density was observed (i.e., the transition charge density (Q T)). We verified that this transition charge is a monotonic function of both the current density and temperature applied during the anodisation, which indicated that Q T is an intrinsic response of this system. The oxide morphology and microstructure were characterised using SEM and X-ray diffraction experiments (XRD) techniques. X-ray diffraction analysis revealed that the change in voltage oscillation was correlated with oxide microstructure changes during the breakdown process. © 2012 Springer-Verlag Berlin Heidelberg.