Search

This work investigates the synthesis and the corrosion inhibitor efficiency ceria nanoparticles may exert on steel reinforcement in an alkaline solution of saturated Ca(OH)2 + 0.5 M CaCl2 up to 50°C. The corrosion mechanisms are thoroughly investigated by electrochemical and various characterization techniques. The electrochemical results show that ceria nanoparticles act as an anodic inhibitor and provide maximum inhibition efficiency (80%) at a concentration of 800 ppm. The resulting surface is smooth and free from corrosion products due to the formation of a physically adsorbed film according to the thermodynamic calculations. [ABSTRACT FROM AUTHOR]

In the present paper, cerium nitrate salt was used as a green inhibitor to improve the corrosion resistance of mild steel in 0.1 M Na2SO4 solution. To increase the barrier effect and film stability of the protective layer, polyethylene glycol (PEG) was added. The corrosion tests were evaluated using d.c polarization techniques and electrochemical impedance spectroscopy. The composition and morphology of the sample surface were characterized using Raman spectroscopy and MEB/EDS analysis. The results show that the presence of PEG improved relatively the corrosion resistance of mild steel due to the removal of cracks, the pores blocking the formed film and the enhancement of adhesion and compactness of the cerium‐based film. Consequently, the protective film became more coherent on the steel surface. Furthermore, the potentiodynamic polarization indicated that the Ce3+/PEG system behaved as a mixed‐type inhibitor with the dominant effect of the cathodic part. [ABSTRACT FROM AUTHOR]

Habitat destruction is a growing threat to biodiversity and ecosystem services. The ecological consequences of habitat loss and fragmentation involve reductions in species abundance and even the extinction of species and their interactions. However, we do not yet understand how habitat loss alters the coevolutionary trajectories of the remaining species or how coevolution, in turn, affects their response to habitat loss. To investigate this, we develop a spatially explicit model which couples metacommunity and coevolutionary dynamics. We show that, by changing the size, composition and structure of local networks, habitat destruction increases the diversity of coevolutionary trajectories of mutualists across the landscape. Conversely, in antagonistic communities, some species increase while others reduce their spatial trait heterogeneity. Furthermore, we show that while coevolution dampens the negative effects of habitat destruction in mutualistic networks, its effects on the persistence of antagonistic communities tend to be smaller and less predictable. [ABSTRACT FROM AUTHOR]

The corrosion mechanisms of T24, T92, VM12, and AISI 304 steels are studied under the influence of NaCl–KCl, NaCl–Na2SO4, and KCl–K2SO4 salt mixtures in a dry air atmosphere at 650°C for 15 days. NaCl–KCl was the most aggressive deposit and AISI 304 stainless steel exhibited the highest corrosion resistance. There was no relation between the Cr content of the ferritic steels and their corrosion resistance in NaCl–KCl. In contrast, the resistance of high‐Cr steels was better when exposed to NaCl–Na2SO4 and KCl–K2SO4. The high‐Cr and the low‐Cr steels were more susceptible to NaCl–Na2SO4 and to KCl–K2SO4, respectively. [ABSTRACT FROM AUTHOR]

The Hermansky–Pudlak syndrome (HPS) is a rare genetic disorder. We report three cases from a family of 12 siblings, with six albinos, of whom four and the father had pulmonary fibrosis (PF). Case 1 was admitted to our hospital due to increasing dyspnoea and history of gynaecological bleeding. Pulmonary function test showed a restrictive airflow pattern, high‐resolution computed tomographic scan demonstrated interstitial lung disease (ILD), and platelet aggregation was compromised with a reduced number of platelet dense bodies. The family history revealed endogamy and 11 members with suspected HPS. One of the albino sisters and the father had passed away with unidentified ILD, an albino brother died 14 years earlier, his autopsy had shown collections of ceroid pigments in the lungs, consistent with HPS, and another brother was followed up at our hospital for ILD and compromised platelet aggregation. This family probably has the highest number of members affected by HPS in Spain. [ABSTRACT FROM AUTHOR]

In this study, the effect of temperature on corrosion inhibition is studied in the absence and presence of an optimal concentration of cerium nitrate (600 mg/L) as an inhibitor of mild steel in sodium chloride. Corrosion tests are carried out through electrochemical techniques such as impedance spectroscopy and d.c. polarization measurements. The surface morphology of the films is investigated by optical microscopy, white‐light interferometry, and scanning electronic microscopy, coupled with energy‐dispersive spectroscopy analysis for chemical composition. The results obtained show that the activation energy for the corrosion inhibition process to occur increases in the presence of a cerium nitrate inhibitor. However, the corrosion resistance of mild steel is somewhat lost upon increasing the solution temperature up to 55°C, which leads to more cracked films. The enthalpy and entropy values suggest a mixed mechanism of chemisorption and physisorption inhibition, with a major dominance of physisorption control. [ABSTRACT FROM AUTHOR]

The effects of the modification of the pH in 0.1 M cerium nitrate solutions in the elaboration and corrosion resistance of ceria based coatings on carbon steel are investigated. Increasing the concentration of acetic acid impedes an efficient electrodeposition. At low concentrations, acetic acid seems to prevent the precipitation of Ce(OH)3 and the formation of even films of cerium oxides is favored. The increase of pH through the addition of NaOH to the cerium nitrate solutions with 0.008 M of acetic acid is shown to provide superior corrosion resistance for exposures in air and immersed in 0.5 M NaCl for 30 days. The effects of the modification of the pH in 0.1 M cerium nitrate solutions in the elaboration and corrosion resistance of ceria based coatings on carbon steel are investigated. Increasing the concentration of acetic acid impedes an efficient electrodeposition. The increase of pH through the addition of NaOH to the cerium nitrate solutions with 0.008 M of acetic acid is shown to provide superior corrosion resistance. [ABSTRACT FROM AUTHOR]

The Direct Approach: Enones possessing appendant allylic carbonates react directly with diorganozinc reagents in the presence of zinc diiodide [ZnI(2)] to provide 5- and 6-membered ring products of tandem or domino conjugate addition-cycloallylation in good to excellent yield. In a related copper-free transformation, allylic carbonates are found to engage in direct allylic substitution with diorganozinc reagents.