Electrodeposited manganese oxides as efficient photocatalyst for the degradation of tetracycline antibiotics pollutant

One of the important environmental challenges of the 21st century is the effective removal of pollutants from the aquatic environment. In this study, electrodeposited manganese oxides (MnyOx) films were applied as visible-light-driven photocatalyst for the removal and mineralization of Tetracycline (TC) antibiotics. The photocatalytic activity of as-deposited and annealed MnyOx was tested at different pH values using LED visible illumination, resulting in 92.4 % of TC mineralization efficiency after 180 min for the best performing manganese oxide. Quenching experiments showed that hydroxyl radicals (radical dotOH) are the main active species responsible for the TC degradation. The photocorrosion of MnyOx has been studied by quantifying the concentration of the dissolved manganese cations during the photocatalytic experiments. By comparing the catalyst mass loss with the % of TC mineralization, we revealed that the degradation of the oxide surface structure is the factor that, more than the photocorrosion, is limiting the photocatalytic activity of MnyOx films. Finally, the photocatalytic mechanism of TC mineralization is proposed based on the detection of the intermediates species of the mineralization process by High-Performance Liquid Chromatography Mass-Spectroscopy. The facile synthesis process and the superior mineralization rate can open up a new approach for the possible large-scale utilization of electrodeposited MnyOx films as an effective visible light photocatalyst

Hard X -Ray Photoelectron Spectroscopy (HAXPES) characterisation of electrochemical passivation oxide layers on Al-Cr-Fe Complex Metallic Alloys (CMA).

A Hard X-ray Photoelectron Spectroscopy (HAXPES) characterisation of the passivation layers formed by electrochemical polarisation of Al–Cr–Fe complex metallic alloys is presented. By employing X-ray excitation energies from 2.3 to 10.0 keV, the depth distributions of Al- and Cr-oxide and hydroxide species in the (Al,Cr)-containing passive layers could be determined. Simultaneous analyses of the shallow Al 2s and deep Al 1s core level lines (respectively, more bulk- and surface-sensitive) provided complementary information to effectively determine the depth-resolved contributions of hydroxide and oxide species within the passivation layer. A Cr threshold concentration of 18 (at.%) was found for effective passivation at pH 1

Calculated phase diagrams, iron tolerance limits, and corrosion of Mg-Al alloys

The factors determining corrosion are reviewed in this paper, with an emphasis on iron tolerance limit and the production of high-purity castings. To understand the iron impurity tolerance limit, magnesium phase diagrams were calculated using the Pandat software package. Calculated phase diagrams can explain the iron tolerance limit and the production of high-purity castings by means of control of melt conditions; this is significant for the production of quality castings from recycled magnesium. Based on the new insight, the influence of the microstructure on corrosion of magnesium alloys is reviewed

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Biocorrosion Zoomed In: Evidence for Dealloying of Nanometric Intermetallic Particles in Magnesium Alloys

ISSN:0935-9648ISSN:1521-409

Silicon Corrosion in Neutral Media: The Influence of Confined Geometries and Crevice Corrosion in Simulated Physiological Solutions

Silicon (Si) based implantable components are widely used to restore functionalities in the human body. However, there have been reported instances of Si corroding after only a few years of implantation. A key parameter often overlooked when assessing Si stability in-vitro, is the added constricting geometries introduced through in-vivo implantation. The influence of crevices and confined solutions on the stability of Si is presented in this study, considering two simulated physiological solutions: 0.01 M phosphate buffered saline (PBS) and HyClone Wear Test Fluid (WTF). It was found that Si is highly vulnerable to corrosion in confined/crevice conditions. High pitting corrosion susceptibility is found in a crevice, whereas a dissolution rate of ca. 3.6 nm/h at body temperature occurred due to local alkalization within a confined cathodic area. The corrosion rates could be increased by elevating the temperature and yielded linear Arrhenius relations, with activation energies of 106 KJ/mol in 0.01MPBS and 109 KJ/mol in HyClone WTF, corresponding to a phosphorous-silicon interaction mechanism. Phosphorous species favored corrosion and contributed to enhanced Si dissolution, while chlorides were not so influential, and applied anodic potential induced pseudo-passivation. These results highlight the importance geometrical configurations can have on a material's surface stability. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited

The influence of yttrium (Y) on the corrosion of Mg-Y binary alloys

Corrosion of Mg-Y alloys was studied using electrochemical evaluations, immersion tests and direct observations. There were two important effects. in 0.1 M NaCl, the corrosion rate increased with increasing Y content due to increasing amounts of the Y-containing intermetallic. In 0.1 M Na(2)SO(4), the corrosion rate decreased with increasing Y content above 3%, attributed to a more protective surface film, despite the intermetallic. The corrosion rate evaluated by electrochemical impedance spectroscopy was somewhat smaller than that evaluated from H evolution as expected from the Mg corrosion mechanism. A mechanism is proposed for filiform corrosion. Direct in situ corrosion observations revealed that a predominant feature was hydrogen evolution from particular parts of the alloy surface. (C) 2010 Elsevier Ltd. All rights reserved