Synthesis and characterization of bifunctional oxygen electrocatalysts for secondary zinc-air batteries

In an effort to transition from fossil fuel-based production toward a more sustainable global energy economy, large-scale reforms to the energy infrastructure have been taking place in the past few years. The rapid integration of renewable energy sources in the global energy production scheme, along with the electrification of transport, have created a growing market for battery energy storage to cope with the intermittent nature of renewables. Metal-air batteries have recently gained renewed interest as high-energy density, low-cost, light-weight and environmentally friendly alternatives to the Li-ion batteries currently dominating the market. Among metal-air battery technologies, reversible zinc-air batteries are considered the closest to commercialization. However, the poor performance of bifunctional oxygen electrocatalysts, coupled with large overpotentials during charge/discharge cycles and low cyclability are all obstacles that limit their potential. In this work, two classes of materials, i.e. carbon nanotubes (CNTs) and cobalt-manganese spinel-type oxides were investigated as possible candidates for use as active catalyst layer in the air electrode of reversible zinc-air batteries. The electrocatalytic activity for oxygen evolution (OER) and oxygen reduction (ORR) reactions of the prepared materials was assessed and compared with that of state-of-the-art catalysts (Pt/C and IrO2). In an attempt to better understand the structural origin of the electrocatalytic activity of the materials investigated, common microscopic and spectroscopic characterization techniques (SEM, TEM, Raman, EDX, XRD, XPS) were employed. The results showed promising prospects for the development of efficient and stable bifunctional oxygen electrocatalysts using hybrids of cobalt-manganese spinel oxides and nitrogen-doped CNTs. The performance of these hybrids was generally found to be in good agreement with the results reported in literature on similar materials. New directions for the optimization of the synthetic methods used in this work can be furhter explored in the future in order to enhance the structural and electrocatalytic properties of the synthesized electrocatalysts

Crinoid phylogeny: a preliminary analysis (Echinodermata: Crinoidea)

We describe the first molecular and morphological analysis of extant crinoid high-level inter-relationships. Nuclear and mitochondrial gene sequences and a cladistically coded matrix of 30 morphological characters are presented, and analysed by phylogenetic methods. The molecular data were compiled from concatenated nuclear-encoded 18S rDNA, internal transcribed spacer 1, 5.8S rDNA, and internal transcribed spacer 2, together with part of mitochondrial 16S rDNA, and comprised 3,593 sites, of which 313 were parsimony-informative. The molecular and morphological analyses include data from the bourgueticrinid Bathycrinus; the antedonid comatulids Dorometra and Florometra; the cyrtocrinids Cyathidium, Gymnocrinus, and Holopus; the isocrinids Endoxocrinus, and two species of Metacrinus; as well as from Guillecrinus and Caledonicrinus, whose ordinal relationships are uncertain, together with morphological data from Proisocrinus. Because the molecular data include indel-rich regions, special attention was given to alignment procedure, and it was found that relatively low, gene-specific, gap penalties gave alignments from which congruent phylogenetic information was obtained from both well-aligned, indel-poor and potentially misaligned, indel-rich regions. The different sequence data partitions also gave essentially congruent results. The overall direction of evolution in the gene trees remains uncertain: an asteroid outgroup places the root on the branch adjacent to the slowly evolving isocrinids (consistent with palaeontological order of first appearances), but maximum likelihood analysis with a molecular clock places it elsewhere. Despite lineage-specific rate differences, the clock model was not excluded by a likelihood ratio test. Morphological analyses were unrooted. All analyses identified three clades, two of them generally well-supported. One well-supported clade (BCG) unites Bathycrinus and Guillecrinus with the representative (chimaeric) comatulid in a derived position, suggesting that comatulids originated from a sessile, stalked ancestor. In this connection it is noted that because the comatulid centrodorsal ossicle originates ontogenetically from the column, it is not strictly correct to describe comatulids as unstalked crinoids. A second, uniformly well-supported clade contains members of the Isocrinida, while the third clade contains Gymnocrinus, a well-established member of the Cyrtocrinida, together with the problematic taxon Caledonicrinus, currently classified as a bourgueticrinid. Another cyrtocrinid, Holopus, joins this clade with only weak molecular, but strong morphological support. In one morphological analysis Proisocrinus is weakly attached to the isocrinid clade. Only an unusual, divergent 18S rDNA sequence was obtained from the morphologically strange cyrtocrinid Cyathidium. Although not analysed in detail, features of this sequence suggested that it may be a PCR artefact, so that the apparently basal position of this taxon requires confirmation. If not an artefact, Cyathidium either diverged from the crinoid stem much earlier than has been recognised hitherto (i.e., it may be a Palaeozoic relic), or it has an atypically high rate of molecular evolution

A resilience engineering approach to safety excellence in the maintenance of oil and gas assets.

The established approach to safety management has failed to handle socio-technical systems that have become more complex. The main argument is this approach is based on assumptions that systems are protected against accidents by barriers (well-trained people, redundant mechanisms and safety devices, and procedures and safe systems of work). Complex systems, such as maintenance, are actually labour intensive; maintenance staff often works under pressure to finish tasks as rapidly as possible. They continuously adapt and make adjustments using available resources, time, knowledge, and competence to achieve success. Thus, they are accidents prone. Human factors inherent to maintenance accidents are most times difficult to identify. Research in this area in the oil and gas industry in maintenance management is limited in comparison to the aviation and nuclear sectors. Therefore, it has been suggested to overcome this lack by exploring the maintenance system and identifying appropriate methods and tools that lead a system to safety excellence. Resilience engineering (RE) approach has been found the suitable solution. Moreover, four system abilities (cornerstones of RE: ability to respond, to monitor, to anticipate, and to learn) have been identified to characterise the resilience of a system; if these abilities are known and increased, it will make the system As High Resilient As Possible (AHRAP). However, there is a need to bridge between RE theory and practice. Particularly, a tool that measures these abilities lacks in the oil and gas industry, specifically within the maintenance system. In doing so, a framework based on a Gap Analysis (GA) was outlined. A tool, the MAintenance System Resilience Assessment Tool- MASRAT, was developed to assess current system resilience and identify strategies for improvement to achieve safety excellence. The maintenance system of SONATRACH was explored by the analysis of the system documentation and processes, interviews with maintenance staff, questionnaires, field observations, storytelling, and functional analysis. MASRAT has been validated by means of congruency and principal components analysis, PCA (content validity), and Cronbachs alpha (reliability). An expert panel testing was carried out to test its usability. The exploration of the system came up with a snapshot of daily activities as well as a better understanding of the maintenance system. The study identified the most significant human factors (resources, time pressure, and supervision/coordination) and their probable impact on plant safety. The elements of the system were found tightly coupled, hence the system complex. Stories describing the continuous adaptations of people to achieve assigned objectives were collected. On the other hand, MASRAT was validated. All items were rated above 0.75 in congruency test. The results of PCA for the three selected factors confirmed the items may be clustered after extraction into four components which interpretation represents the four cornerstones of RE. The analysis showed MASRAT is reproducible. Cronbachs alpha results were found higher than what is required (0.7). MASRAT was found usable by maintenance expert panel. It was used to measure the maintenance department resilience. Strategies that may lead the system from current maturity level to excellence were identified. Eventually, recommendations were made to management to be implemented both at corporate and department levels. For the first time, the maintenance department resilience of petroleum assets was measured to fill in the gap between RE theory and practice. Besides, this can be of benefit to the petroleum industry by a better knowledge of the maintenance working environment and human factors impact on safety and by profiles determination and improvement strategies identification

ESTIMATE OF THE METALLIC CONTAMINATION OF THE URBAN EFFLUENTS BY THE EFFLUENTS OF THE MOHAMED V HOSPITAL OF MEKNES

The Mohamed V hospital of Meknes is one of the most important establishments for public health in the entire region of Meknes-Tafilalet; it is also one of the biggest sanitary structures of Morocco. According to the classification of the American Hospital Association (American Hospital Association [AHA], 1986) based on the number of active beds, this hospital belongs to class 7, with a real bed capacity of 531 beds among which 416 are functional, hence this has led to the importance of the study of the impacts of its effluents on the environment. Wastewaters of this hospital contain pollutions of microbiological, chemical, organic, mineral and metallic nature. They are rejected in the sewer system of the city without any preliminary treatment and has a loosened open-air at the level of Aïn Choubbik district where they are reused by the local residents for the irrigation of truck farm, cereal and tree-dwelling farm. Moreover, the major part of these wastewaters is poured into Bourouh river, in particular during pluvial period. Consequently, we may note direct harmful impacts on the health of Man as well as on the environment with its diverse compartments, water (Surface Water and subsoil water), ground and air. Thus, we will try using this present study to evaluate the pollution rate by elements in state of trace, taking a case of heavy metals effluents of the Mohamed V hospital of Meknes and the consequences it could have on the environment and as well as the proposed solutions. So, we are also going to estimate the pollution rate by these elements at the levels of urban wastewaters of the Ain Choubbik district receptacles of the hospital effluents

The place of cognition and metacognition in the Algerian EFL Middle School Course in receptive, productive skills and grammar

The educational reform which has been launched in the 2000’s brought a big shift in the Algerian educational learning process, a shift which has brought a focus on cognition, metacognition, critical thinking and knowledge construction. Among the competencies that have been given due concern, the intellectual competency is regarded as central in the recent educational reform movement

LMD System: How to Organise Support Pedagogy in Retake Courses

The LMD system is designed and implemented to maximize students’ chances of success. However, after some years of its implementation in different departments of our faculty, including the department of English, figures show that success rates are often lower than what they used to be in the old system. Measures should therefore be taken to handle students’ failure, measures that must be in line with both the spirit of the LMD and the background realities of Algerian universities.In the light of this situation, this paper will be concerned with support pedagogy in re-take courses and the way to cope with the large number of students in these classes. It is intended to provide a battery of innovative and effective measures that address English teachers’ concerns over course design and classroom management

Corte – Plateau d’Alzu

Le plateau d’Alzu se situe dans le nord de la Corse, au sud-ouest de Corte (à environ 8,5 km à vol d’oiseau), à une altitude de 1 588 m, sur une crête qui sépare les vallées de la Restonica et du Tavignano, dans une zone à pente modérée. Les traces d’exploitation préhistoriques, encore visibles actuellement sur une surface d’environ 46 ha, témoignent de l’existence d’activités d’extraction et de transformation de la rhyolite. Il s’agit d’une rhyolite homogène, compacte et cassante (cassure co..

Un cas rare d’hémangiopéricytome malin du membre inférieur

L’hémangiopericytome est une tumeur vasculaire rare classée comme sarcome des tissus mous, elle peut être bénigne ou maligne, elle prend naissance au niveau des péricytes qui sont des cellules localisées au niveau de la lame basale de l’endothélium des capillaires ce qui explique son caractère ubiquitaire. Leur traitement de référence est la chirurgie souvent complétée d’une radiothérapie. Nous rapportons un cas d’un énorme hémangiopericytome malin du pied chez une patiente de 28 ans qui nous a été adressé pour une tumeur du pied gauche nécrosée est infectée avec une biopsie qui a été réalisée revenant en faveur d’un hémangiopericytome le bilan d’extension comportant une scintigraphie osseuse et un scanner thoraco-abdomino-pelvien n’a pas objectivé de localisation secondaire Vu la taille de la tumeur et son caractère nécrosé et infectée un traitement chirurgical radical par une amputation transtibiale a été décidé après le consentement de la patiente

Vallée du Prunelli

Cette prospection diachronique s’inscrit dans le cadre du programme européen LEADER porté par le Groupe d’action local (GAL) du pays d’Ajaccio – action « Construire et développer une offre économique territoriale par la mise en valeur des acteurs, des compétences et la valorisation des ressources locales ». Un travail de collaboration est en cours avec H. Paolini-Saez (LRA), chargée de réaliser une prospection diachronique sur la vallée de la Gravona. Les résultats obtenus sur l’occupation hu..

Asco – Massif du Cintu

La prospection pédestre réalisée dans la haute vallée d’Asco en août 2017 avait pour objectif d’identifier des gîtes de rhyolite (potentiels ou présentant une exploitation préhistorique avérée) et des traces d’occupation néolithique (atelier, habitat). Elle s’est inscrite dans la continuité de recherches universitaires (Ameziane-Federzoni 1999, 2011) et d’un PCR sur les matières premières lithiques de la Corse (Bressy et al. 2014). Les indices récoltés au cours de ces recherches ont permis d’..