Effect of the metallic substrate and zinc layer on the atmospheric corrosion resistance of phosphatized and painted electrogalvanized steels

In this work, the influence of the metallic substrate and zinc layer on the atmospheric corrosion resistance of phosphatized and painted electrogalvanized steels was evaluated. For this purpose two types of electrogalvanized steels were used, one with drawing quality carbon steel as metallic substrate, and the other one with a substrate of Ni–Cu–Cr added carbon steel. The corrosion resistance was determined by accelerated and non‐accelerated corrosion tests, using cyclic test chambers and field tests in industrial and marine atmosphere. The mean corrosion advance and the maximum corrosion penetration of samples were measured using image analysis techniques. The study showed that the substrate and zinc layer mass play a decisive role on the atmospheric corrosion resistance of the phosphatized and painted electrogalvanized steels. It was also verified that it is possible to use smaller zinc layer masses without compromising the corrosion resistance of the material, provided that the metallic substrate has characteristics of atmospheric corrosion resistance, thus contributing to the improvement of the zinc coated steels.     

Catalytic activity evaluation for hydrogen production via autothermal reforming of methane

A nickel catalyst (5.75 wt.%) supported on gamma-alumina was evaluated through autothermal reforming of methane (ATR). The reforming process was pointed to hydrogen production, following thermodynamic and stoichiometric predictions. The catalyst was characterised by several methods including atomic absorption spectroscopy (AAS), B.E.T.-N₂, X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal analyses (thermogravimetry, TG; derivate thermogravimetry, DTG; and differential thermal analysis, DTA). Experimental evaluations in a fixed-bed reactor (1023–1123 K, 1.00 bar, 150–400 cm³/min feed) presented methane conversions in the range of 40–65%. The effluent mixtures provided hydrogen yields in the range of 78–84%, carbon monoxide 3–14%, and carbon dioxide 5–18%. High molar H₂/CO ratios, ranging from 8 to 90, were obtained. Operating autothermal conditions (excess of steam, 1023–1123 K, 1.00 bar) provided low coke formation and high hydrogen selectivity (81%) for methane reforming.     

Three-dimensional analysis of the 16 nm urothelial plaque particle: luminal surface exposure, preferential head-to-head interaction, and hinge formation

The luminal surface of mouse urothelium in contact with the urine is almost entirely covered with plaques consisting of uroplakin-containing particles that form p6 hexagonal crystals with a center-to-center distance of 16 nm. A combination of quick-freeze/deep-etch images and our previous negative staining data indicate that the head domain of the uroplakin particle, which is exposed without an extensive glycocalyx shield, interacts closely with the head domains of the neighboring particles, while the membrane-embedded tail domains are farther apart; and that urothelial particles and plaques are not rigid structures as they can change their configuration in response to mechanical perturbations. Based on these data, we have constructed three-dimensional models depicting the structural organization of urothelial particles and plaques. Our models suggest that the head-to-head interaction may play a key role in determining the shape and size of the urothelial plaques. These models can explain many properties of urothelial plaques including their unique shape, detergent-insolubility, and morphological changes during vesicle maturation.     

The National Agricultural Laboratories of Brazil and the control of residues and contaminants in food

The laboratory activity of the Ministry of Agriculture, Livestock and Food Supply in Brazil has a history that is richer than most people are aware of. The institutions that today are known as National Agricultural Laboratory - Lanagros - were once a smaller initiative that suffered ups and downs throughout the decades. The recognition that the Lanagros have today - as reference centres with open communication channels with some of the world's greater laboratories in residue and contaminants in food analyses - is the fruit of several years of hard work, good ideas and a strong will never to let down society. Today the Lanagros act not only by performing analyses for the monitoring and investigation programmes, but also in the research and development of analytical methods, providing technical advice on the elaboration of guidelines and normatives, international negotiation and the evaluation of other laboratories. The Lanagros work in an ISO 17025 environment, and they are now being directed and prepared to be able to respond to outbreaks and crises related to the presence of residues and contaminants in food, with the readiness, quickness and reliability that an emergency requires. Investments are allocated strategically and have been giving concrete results, all to the benefit of consumers.     

Evaluation of the atmospheric corrosion resistance of AISI A-36 steel painted with coatings based on epoxy and poly(urethane) resins using semi-accelerated testing

The influence of temperature, humidity, salinity, and the number of wet-dry cycles in the atmospheric corrosion resistance of the AISI A-36 steel, painted with coatings based on epoxy and poly(urethane) resins was studied. The aim of this work is to present an alternative to the accelerated and field tests developing a semi-accelerated test for evaluating the resistance and durability of a protection system that is applied to a specific environment for one year. The samples were exposed in a corrosion cyclic test chamber for 2000 h with fixed parameters of temperature, relative moisture of air, salinity, and a number of dry-wet cycles. Mass loss of substrate in the scratch area was measured after each 250 h of testing. The second stage of research was the sensibility analysis of the corrosion rate with the change of the reference test parameters. The third stage was the testing of the samples using the cyclic test for 750 h, and the transfer of samples to a marine atmosphere exposure for one year. The mass loss was measured after each 60-day period of testing. Material characterization involved scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray fluorescence spectroscopy. After polynomial adjustment of the mass loss function associated with the sensibility analysis of the parameter alteration, the estimated life span of the samples ranged from 30 to 38 months.