Film-Forming Amines for the Corrosion Protection of Carbon Steels in Nuclear Power Plant Secondary Circuit Conditions: An Impedance Study

Octadecylamine (ODA) has been the subject of numerous investigations for the corrosion protection of carbon steels in nuclear pressurized water reactors (PWR). In the present work, electrochemical impedance spectroscopy was used to study and to compare the ODA behavior after different treatment temperatures (from 80 °C to 275 °C) representative of the secondary circuit of the PWR. The ODA films were characterized at room temperature. The impedance data analysis allowed the ODA film parameters (thickness and permittivity) to be obtained. The ODA film thickness was independent of the treatment conditions and was about 20 nm. At 120 °C and 220 °C, the presence of magnetite, formed during the treatment in the autoclave, strongly improved the corrosion protection afforded by the ODA films. An instantaneous inhibitive efficiency of 99.9% was assessed. At 275 °C, thermal degradation of the ODA molecules was shown

Impedance analysis of film-forming amines for the corrosion protection of a carbon steel

Octadecylamine (ODA) is a well-known organic inhibitor for the corrosion protection of carbon steels. In the present study, electrochemical impedance data analysis was performed to extract physical parameters of the ODA thin film that formed on a P275 carbon steel surface. First, surface observations and contact angle measurements showed the steel surface modification after the ODA treatment linked to the adsorption of an organic hydrophobic thin film. X-ray photoelectron spectroscopy confirmed the presence of a very thin organic layer and revealed the presence of iron oxide/hydroxide underlying the ODA film. The impedance data analysis with a power-law distribution of resistivity in the organic film allowed the permittivity and thickness to be extracted. Finally, from the impedance results with and without ODA, the instantaneous corrosion inhibition efficiency was determined

Les conventus de Lydie (fin IIe-IIIe siècle de notre ère) : Louis Robert, Konrad Kraft et les analyses élémentaires

led historians to assume the existence of central workshops. In a study published in 1967, L. Robert hypothesized that capitals of conventus could have fulfilled that function and he placed much hope in K. Kraft’s upcoming study. Despite the publication of the latter in 1972, the question remains debated. Elemental analyses of coins struck in the Lydian conventus sheds new light but do not allow confirming L. Robert’s hypothesis.Résumé -Les liaisons de coins de droit entre monnaies provinciales micrasiatiques issues de cités différentes ont conduit les historiens à imaginer l’existence d’ateliers centraux. Dans une étude parue en 1967, L. Robert émettait l’hypothèse que les capitales de conventus auraient pu remplir cette fonction, et plaçait beaucoup d’espoir dans l’étude de K. Kraft. Malgré la publication de celle-ci en 1972, la question reste toujours débattue. Des analyses élémentaires de monnaies frappées dans les conventus lydiens apportent un éclairage nouveau sans toutefois confirmer l’hypothèse de L. Robert.Hochard Pierre-Olivier, Blet-Lemarquand Maryse, Baux Dominique. Les conventus de Lydie (fin IIe-IIIe siècle de notre ère) : Louis Robert, Konrad Kraft et les analyses élémentaires. In: Revue numismatique, 6e série - Tome 176, année 2019 pp. 139-180

Influence of Water Radiolysis on the Passive Properties of 316L‐Stainless Steel

International audienceAbstractThis work aims to study the effect of radiolytic species induced by water radiolysis on the passive behavior of 316L stainless steel. For this purpose, the stainless steel/neutral and aerated 0.02 M Na2SO4, electrolyte solution interface was irradiated with proton beams. A wide range of energies between 2 and 16 MeV was selected, varying the maximum of the energy deposition between 0.5 and 122 μm in water from the interface. The irradiation experiments were performed at the CEMHTI cyclotron in Orléans and the 4 MV Van de Graaff accelerator at IP2I in Lyon (France). A dedicated irradiation device implemented with a 3‐electrode cell dedicated to perform electrochemical measurements allows to measure the surface reactivity of the stainless steel as a function of the irradiation conditions. Results show that whatever the beam energy, the corrosion potential remains unchanged. It indicates that the very short‐lived, highly reactive radiolytic species drive the corrosion potential and not only the recombination products such H2O2 or H2. The stainless steel remains in the passive state whatever the irradiation conditions. However, it is shown that, during irradiation, the passive film is less protective. This evolution is attributed to radiolysis of bound water molecules in the passive film.</jats:p

Electrochemical behaviour of austenitic stainless steel under tribological stresses and irradiation

International audienceAn experiment was developed to characterise the behaviour of 316 L stainless steel under the combined effects of corrosion, tribology, and irradiation. This original experiment shows that radiolysis, through the production of free radicals and H2O2, leads to an oxidising medium. The electrochemical behaviour of the material from the recorded polarisation curves and electrochemical impedance spectroscopy measurements indicates that the passive film under irradiation is a Cr oxi-hydroxide layer. The layer has more formative thickness under irradiation. When the irradiation is interrupted, the passive film is identical to that observed before irradiation. The repassivation is faster during irradiation and friction

Enrichment of LOVD-USHbases with 152 USH2A Genotypes Defines an Extensive Mutational Spectrum and Highlights Missense Hotspots

International audienceAlterations of USH2A, encoding usherin, are responsible for more than 70% of cases of Usher syndrome type II (USH2), a recessive disorder that combines moderate to severe hearing loss and retinal degeneration. The longest USH2A transcript encodes usherin isoform b, a 5,202-amino-acid transmembrane protein with an exceptionally large extracellular domain consisting notably of a Laminin N-terminal domain and numerous Laminin EGF-like (LE) and Fibronectin type III (FN3) repeats. Mutations of USH2A are scattered throughout the gene and mostly private. Annotating these variants is therefore of major importance to correctly assign pathogenicity. We have extensively genotyped a novel cohort of 152 Usher patients and identified 158 different mutations, of which 93 are newly described. Pooling this new data with the existing pathogenic variants already incorporated in USHbases reveals several previously unappreciated features of the mutational spectrum. We show that parts of the protein are more likely to tolerate single amino acid variations, whereas others constitute pathogenic missense hotspots. We have found, in repeated LE and FN3 domains, a nonequal distribution of the missense mutations that highlights some crucial positions in usherin with possible consequences for the assessment of the pathogenicity of the numerous missense variants identified in USH2A

Missense mutations of conserved glycine residues in fibrillin-1 highlight a potential subtype of cb-EGF-like domains

International audienceIn six index cases/families referred for Marfan syndrome (MFS) molecular diagnosis, we identified six novel mutations in the FBN1 gene: c. to result in Glycine substitutions are located at the third position of a 4 amino acids loop-region of calcium-binding Epidermal Growth Factor-like (cb-EGF) fibrillin-1 domains #5, #9, #24, #25 and #32. Familial segregation studies showing cosegregation with MFS manifestations or de novo inheritance in addition to in silico analyses (conservation, 3D modeling) suggest evidence for a crucial role of the respective Glycine positions. Extending these analyses to all Glycine residue at position 3 of this 4 residues loop in fibrillin-1 cb-EGF with the UMD predictor tool and alignment of 2038 available related sequences strongly support a steric strain that only allows Glycine or even Alanine residues for domain structure maintenance and for the fibrillin functions. Our data compared with those of the literature strongly suggest the existence of a cb-EGF domain subtype with implications for related diseases

Four-Year Follow-up of Diagnostic Service in USH1 Patients

International audiencePURPOSE: The purpose of this study was to establish the mutation spectrum of an Usher type I cohort of 61 patients from France and to describe a diagnostic strategy, including a strategy for estimating the pathogenicity of sequence changes.METHODS: To optimize the identification of Usher (USH)-causative mutations, taking into account the genetic heterogeneity, preliminary haplotyping at the five USH1 loci was performed to prioritize the gene to be sequenced, as previously described. Coding exons and flanking intronic sequences were sequenced and, where necessary, semiquantitative PCR and multiplex ligation-dependent probe amplification (MLPA) were performed to detect large genomic rearrangements.RESULTS: Four years ' experience confirms that the chosen approach provides an efficient diagnostic service. Sixty-one patients showed an abnormal genotype in one of the five USH1 genes. Genetic heterogeneity was confirmed, and, although MYO7A remains the major gene, involvement of other genes is considerable. Distribution of missense, splicing, premature termination codons (PTCs; due to point substitution and small deletions/ or insertions), and large genomic alterations was determined among the USH genes and clearly highlights the need to pay special attention to the diagnostic approach and interpretation, depending on the mutated gene.CONCLUSIONS: Over the 4 years of a diagnostic service offering USH1 patient testing, pathogenic genotypes were identified in most cases (>90%). The complexity and heterogeneity of mutations reinforces the need for a comprehensive approach. Because 32% of the mutations are newly described, the results show that a screening strategy based on known mutations would have solved less than 55% of the cases

The Study of a 231 French Patient Cohort Significantly Extends the Mutational Spectrum of the Two Major Usher Genes MYO7A and USH2A

International audienceUsher syndrome is an autosomal recessive disorder characterized by congenital hearing loss combined with retinitis pigmentosa, and in some cases, vestibular areflexia. Three clinical subtypes are distinguished, and MYO7A and USH2A represent the two major causal genes involved in Usher type I, the most severe form, and type II, the most frequent form, respectively. Massively parallel sequencing was performed on a cohort of patients in the context of a molecular diagnosis to confirm clinical suspicion of Usher syndrome. We report here 231 pathogenic MYO7A and USH2A genotypes identified in 73 Usher type I and 158 Usher type II patients. Furthermore, we present the ACMG classification of the variants, which comprise all types. Among them, 68 have not been previously reported in the literature, including 12 missense and 16 splice variants. We also report a new deep intronic variant in USH2A. Despite the important number of molecular studies published on these two genes, we show that during the course of routine genetic diagnosis, undescribed variants continue to be identified at a high rate. This is particularly pertinent in the current era, where therapeutic strategies based on DNA or RNA technologies are being developed