Effet de l’oxygène sur les radiations optiques émises lors de la pulvérisation de l’aluminium par un faisceau d’ions

La présence de l’oxygène au voisinage d’une surface métallique lors d’unbombardement ionique, provoque une décroissance du rendement totalde pulvérisation mais elle modifie considérablement les proportions desdiverses espèces éjectées de cette surface. Dans ce travail, nous noussommes intéressés à l’effet de l’oxygène sur la lumière émise lors de lapulvérisation d’une surface d’aluminium par des ions Kr+ d’énergiecinétique de 5 keV. Le spectre de luminescence relevé à une pression de10-7 Torr est comparé à celui mesuré lorsque la cible est soumise à uneatmosphère d’oxygène. L’examen des intensités des raies spectralesmontre que toutes les raies Al I manifestent une dépendance positiveavec la pression en oxygène alors que des raies Al II manifestent unedépendance négative. Nous avons aussi enregistré que des raies Al IIIrestent insensibles à la présence de ce gaz. Ces observations sontcomparées avec les spectres de luminescences de l’alumine bombardéedans les mêmes conditions expérimentales. Les résultats obtenus sontinterprétés dans le cadre du modèle de transfert d’électrons entre lasurface et la particule éjectée. La validité du modèle suggère qu'en présence de l'oxygène, une structure est formée et dont le schéma debandes d'énergie est intermédiaire entre celui de l'aluminium et celui del'alumine.Mots-clés : pulvérisation, émission optique, aluminium, alumine, modèlede transfert d’électrons; analyse de surface, spectroscopie optique

Impact of bonding defect on the tensile response of a composite patch-repaired structure: Effect of the defect position and size

Adhesive bonding has seen rapid development in recent years, with emphasis to composite patch repairing processes of geometric defects in aeronautical structures. However, its use is still limited given its low resistance to climatic conditions and requirement of specialized labor to avoid fabrication induced defects, such as air bubbles, cracks, and cavities. This work aims to numerically analyze, by the finite element method, the failure behavior of a damaged plate, in the form of a bonding defect, and repaired by an adhesively bonded composite patch. The position and size of the defect were studied. The results of the numerical analysis clearly showed that the position of the defect in the adhesive layer has a large effect on the value of J-Integral. The reduction in the value of J-Integral is also related to the composite stacking sequence which, according to the mechanical properties of the ply, provides better load transfer from the plate to the repair piece through the adhesive. In addition, the increase in the applied load significantly affects the value of the J-Integral at the crack tip in the presence of a bonding defect, even for small dimensions, by reducing the load transfer.info:eu-repo/semantics/publishedVersio

Metal corrosion inhibition by triazoles : A review

Metal corrosion and the prospects of inhibiting this process have received much interest from society and scientific research. The annual global cost of corrosion is $2.5 trillion, equivalent to roughly 3.4% of the world's gross domestic product. Implementing corrosion prevention best practices could result in global savings of 15-35% of that cost. Numerous studies were documented and dedicated on the triazole nucleus based compounds as fascinating corrosion inhibitors of various metals in hostile media. Their unique electronic structure possessing conjugated pi and unshared pairs of electrons on the nitrogen atoms facilitates their adsorption on metal surfaces. Thus, physical and chemical interactions between the active centers of triazoles and d-orbitals of metallic materials occur to form a film on the surface. The nature of inhibitor activity is disclosed through polarization studies (cathodic, anodic or mixed-type). The range of various substituents on the triazole ring offers a vast array of inhibitory effects. temperature and inhibitor concentration effects must also be regarded when evaluating the corrosion activation and adsorption parameters supported further by the quantum chemical parameters such as DFT and molecular dynamics simulations. In this review, we looked through several instances of the use of distinct substituted triazole nucleus based compounds as significant corrosion inhibitors for different metals in various aggressive media.Peer reviewe

Indicators of patients with major depressive disorder in need of highly specialized care: A systematic review

Objectives Early identification of patients with major depressive disorder (MDD) that cannot be managed by secondary mental health services and who require highly specialized mental healthcare could enhance need-based patient stratification. This, in turn, may reduce the number of treatment steps needed to achieve and sustain an adequate treatment response. The development of a valid tool to identify patients with MDD in need of highly specialized care is hampered by the lack of a comprehensive understanding of indicators that distinguish patients with and without a need for highly specialized MDD care. The aim of this study, therefore, was to systematically review studies on indicators of patients with MDD likely in need of highly specialized care. Methods A structured literature search was performed on the PubMed and PsycINFO databases following PRISMA guidelines. Two reviewers independently assessed study eligibility and determined the quality of the identified studies. Three reviewers independently executed data extraction by using a pre-piloted, standardized extraction form. The resulting indicators were grouped by topical similarity, creating a concise summary of the findings. Results The systematic search of all databases yielded a total of 7,360 references, of which sixteen were eligible for inclusion. The sixteen papers yielded a total of 48 unique indicators. Overall, a more pronounced depression severity, a younger age of onset, a history of prior poor treatment response, psychiatric comorbidity, somatic comorbidity, childhood trauma,psychosocial impairment, older age, and a socioeconomically disadvantaged status were found to be associated with proxies of need for highly specialized MDD care. Conclusions Several indicators ar

Plant growth promoting activities of Pseudomonas sp. and Enterobacter sp. isolated from the rhizosphere of Vachellia gummifera in Morocco

The Moroccan endemic Vachellia gummifera grows wild under extreme desert conditions. This plant could be used as an alternative fodder for goats, and camels, in order to protect the Argan forests against overgrazing in Central and Southwestern Moroccan semiarid areas. With the aim to improve the V. gummifera population's density in semiarid areas, we proposed its inoculation with performing plant growth-promoting bacteria. Hence, 500 bacteria were isolated from the plant rhizosphere. From these, 291 isolates were retained for plant growth-promoting (PGP) activities assessment. A total of 44 isolates showed the best phosphates solubilization potential, as well as siderophore and auxin production. The combination of REP-PCR (repetitive extragenic palindromic-polymerase chain reaction) fingerprinting, PGP activities, and phenotypic properties, allowed the selection of three strains for the inoculation experiments. The three selected strains' 16S rRNA sequencing showed that they are members of the Enterobacter and Pseudomonas genera. The inoculation with three strains had diverse effects on V. gummifera growth parameters. All single and combined inoculations improved the plant shoot weight by more than 200%, and the root length by up to 139%, while some combinations further improved protein and chlorophyll content, thereby improving the plant's forage value. The three selected strains constitute an effective inoculum for use in the arid and semiarid zones of southern Morocco.The authors want to thank all the persons who contributed to the achievement of this work. This work was funded by the Hassan II Academy of Science and Technology (AH2ST), in Morocco. B.M. received a grant from the AH2ST. She received also the excellency fellowship Khadija Baddouri in life sciences, from the Horizons foundation, Franc