ExxonMobil (France)

International audience

Abstract Synthetic lubricants were originally developed and used for applications where petroleum products were inadequate (e.g., at extremely high and low temperatures, under extreme wear conditions) or where special characteristics, such as long life, improved equipment efficiency, or non‐flammability, were needed. However, the use of synthetic lubricants is not restricted to special applications, but is also useful when they can provide cost efficiency in areas such as machine reliability, oil life, energy consumption, biodegradability, and safety. Among many successful applications, typical cases where synthetic fluids have clear advantages over conventional lubricants include: high‐temperature lubricants for plastic calenders (significant lengthening of oil‐change intervals, fewer machine shutdowns): worm gear drives under severe service conditions (increase in efficiency, lower operating temperatures); air compressors (elimination of combustible petroleum residues); hydraulic fluid in fire‐resistant applications (mining equipment, pressure casting machines, steam turbine control systems); and high‐speed greased bearings (reduced friction losses). The benefits of synthetic lubricant base stocks are derived not only from their basic molecular structures but also from the absence of harmful molecular species often unavoidably present in conventional mineral oils in small, but significant, concentrations. There are very many compounds in crude oil, and while many, or most, of the harmful ones are removed or upgraded by refining, depending on the methods used, a significant number will inevitably remain in lubricating oil stocks, whether solvent‐ or hydrotreated. Thus, conventional oils comprise a wide variety of molecular species, many of which are not well characterised. In contrast, synthetic products normally are produced by chemical reactions of very pure, small molecules in which pressure, tempesutuse, und the ratio of reactants cun he curefully controlled. Frequently, the synthesis o j the reaction up to the desised end product includes severul steps, each of which necessitutes a pusifcution of the intermediute psoducts. It is this resulting ji‐eedom jhom undesisuhle compounds that gives synthetic lubricants their distinctiiie characteristics. It also contrihutes to their higher cost, compased to mineral oils, the oiserall cost of u synthetic product being the sum of the costs of the raw materials und the costs of the individual reuction steps. It is estimuted thut approximutely 80% of the worldwide synthetic luhsicants market is repsesented by three generic groups: polyulphaolejins (∼45%), organic esteia (∼25%), and polyglycols (∼10%). Of the remaining synthetic luhricunts, phosphate esters and polyhirtenes make up probably the largest sules volumes, with about S% each in total. This paper. provides an overview of the types, characteristics, uses, und udwrztages of synthetic lubricants, based on these major technology categories.

Prolactinoma represents the most frequent hormone-secreting pituitary tumours. These tumours appear in a benign form, but some of them can reach an invasive and aggressive stage through an unknown mechanism. Discovering markers to identify prolactinoma proliferative and invading character is therefore crucial to develop new diagnostic/prognostic strategies. Interestingly, members of the TGFβ-Activin/BMP signalling pathways have emerged as important actors of pituitary development and adult function, but their role in prolactinomas remains to be precisely determined. Here, using a heterotopic allograft model derived from a rat prolactinoma, we report that the Activins orphan type I receptor ALK7 is ectopically expressed in prolactinomas-cells. Through immunohistological approaches, we further confirm that normal prolactin-producing cells lack ALK7-expression. Using a series of human tumour samples, we show that ALK7 expression in prolactinomas cells is evolutionary conserved between rat and human. More interestingly, our results highlight that tumours showing a robust expression of ALK7 present an increased proliferation as address by Ki67 expression and retrospective analysis of clinical data from 38 patients, presenting ALK7 as an appealing marker of prolactinoma aggressiveness. Beside this observation, our work pinpoints that the expression of prolactin is highly heterogeneous in prolactinoma cells. We further confirm the contribution of ALK7 in these observations and the existence of highly immunoreactive prolactin cells lacking ALK7 expression. Taken together, our observations suggest that Activin signalling mediated through ALK7 could therefore contribute to the hormonal heterogeneity and increased proliferation of prolactinomas.

Abstract To solve nonlinear seismic velocity inversion problems, we have developed an automatic velocity-estimation technique based on the stochastic method called multiobjective evolutionary algorithms (MOEA). Semblance and differential semblance are used as objective functions. To cope with the high computational cost, we customized MOEA, added domain knowledge (velocity increases with depth, slowly varies along layers, and so forth), which improves the conditioning of the problem and accelerates convergence. This approach is robust because it can cope with large velocity errors. Computational cost of this algorithm is at least two orders of magnitude faster than other stochastic methods and comparable to that of direct gradient methods.

Antérieurement attribuées à l'Albo-Aptien et considérées comme résultant du diapirisme des évaporites triasiques, les brèches de Bosmendiette se seraient, pour certains auteurs récents, mises en place au Sélandien (Paléocène), dans des canyons sous-marins établis au sein d'un profond sillon, le long de la chaı̂ne des Pyrénées, du Roussillon jusqu'à l'Atlantique. Leur âge serait fondé sur la découverte d'une riche microfaune pélagique de globigérinidés. Nos recherches montrent qu'azoı̈ques à leur base, pourvues de radiolaires et de rares foraminifères benthiques au sommet, ces brèches résultent en réalité de la destruction de boucles de slumps affectant l'« Infralias ». Recouvertes en onlap par les calcaires et marnes de l'Albo-Aptien, elles traduisent, conformément à nos précédentes interprétations, l'effondrement par collapse et le glissement vers le nord, en milieu marin graduellement ouvert, de la plate-forme jurassique, lors de la mise en place du diapir de Béloscare–Apoura, au cours du Crétacé inférieur.

The Pyrenees are the result of the structural inversion of a rift of general direction N110E, established at the articulation of the European and Iberian plates. This rift was created by left-lateral transtension with severe crustal thinning during the latest Early Cretaceous and Mid-Cretaceous. Its inversion, which led to the uplifting of the Pyrenean chain, took place gradually, by transpression from east to west, during the Late Cretaceous followed by an Eocene collision. From historical fieldwork, this note mainly focuses on the rifting period at the scale of the Pyrenean domain. It clearly shows the fundamental role of the stratigraphic approach in structural interpretation. Although synchronous at the scale of the Pyrenees, the Cretaceous extension is more important in the western part of the chain, near the Bay of Biscay. It is therefore at this location, within the Tardets-Mauléon Basin, that the various stages of creation and evolution of the rift could be clearly recognized with, successively: (1) an epirogenic pre-rifting stage, during which the facies lines, submeridian during the Jurassic, gradually change into N110E during the Neocomian before giving way, in the Early Cretaceous (Barremian-Gargasian), to a moderate acceleration of subsidence and, consequently, to the gentle uplift of a southern and western margin, future High Primary Belt (also often called Axial Zone) and Landes Plateau, initiating the next stage; (2) a major, brittle, newly identified rifting stage in the Latest Aptian (Clansayesian) and Early Albian. It is characterized by the installation of elongated lows on the downthrown side of transverse N20 normal faults, active diapirism of the Triassic evaporites and central detachment of the post-Triassic cover. During the Mid-Albian, a major surface of stratigraphic unconformity, often associated to uplift, erosion, and local centripetal gliding of the basin borders, marks a new structural organization, a rapid mantle ascent and the end of this episode. Although obscured by the later Pyrenean compression, the reconstructed basin geometry is interpreted as a “pull-apart” basin associated to a modest left-lateral motion; (3) a late rifting stage characterized by the collapse of the internal zones by rapid mantle cooling. The erosion of the coeval uplift of the southern High Primary Belt and the Landes Plateau feeds the accumulation of the thick, deep and transgressive unconformable formation of the Black Flysch of Mid-Albian to Early Cenomanian age in a larger coalescing basin. Faulting associated with a simple NS distension is only active on the last major border faults; (4) finally, a post-rift stage of Late Cretaceous age illustrated by the establishment of a passively subsiding basin, devoid of major deformations and whose heterogeneity of the previous depocenters is gradually erased. The Pyrenean transpression, later and less marked than in the eastern and central Pyrenees, allowed the conservation of most of these Cretaceous transtensive structures. Within the Tardets-Mauléon Basin, the Pernes and Col d’Urdach sector, the only Pyrenean location where the Mid-cretaceous transtension led to a proven underwater mantle exhumation, illustrates from outcrops the various stages that have marked the history of the Pyrenean Trough. Towards the east, along the Internal Metamorphic Zone, the Lourdes-Bagnères, Baronnies, Ballongue, Aulus and Saint-Paul de Fenouillet-Boucheville Basins, or those, further north like the Camarade and Quillan Basins, successively examined, testify to the same sedimentary and structural evolution. As in the case of the Tardets-Mauléon Basin, we deal here again with “pull-apart” type basins established on a thinned crust, arranged in transtensive or locally transpressive relays and separated by zones of thicker crust and shallower facies successions. The Mid-Albian unconformity is always present, heralding a general drowning of the North Pyrenean Trough and cessation of the extensional activity. The Pyrenean deformation, however, constitutes an obstacle for a precise geodynamic reconstruction, in particular in the eastern and central Pyrénées. Towards the west and north-west, in the South Aquitaine, Parentis and Basque-Cantabrian Basins, where Pyrenean deformation has far less obscured the rifting events, a very comparable Cretaceous geodynamic evolution is observed thus strengthening the present interpretation.

More than 90% of electric motors are operating in Zone 2 explosive gas atmosphere for S1 to S10 applications such as pumps, reciprocating or centrifugal compressors etc. There have been a few recordable incidents in offshore or near-shore facilities in the North Sea within the last twenty years. As a result, a number of safety notices were issued from the Department of Energy- UK, for the use or application of pre-start ventilation or pre-start purging or purged and pressurization on existing or new high voltage motors. The authors discuss the importance of such features in Ex nA motors with respect to the present and most up to date IEC 60079-15 standard of Ex nA motors. At the same time various applications, associated risks, and proper selection of this expensive large motor feature is discussed. Different aspects of design and application is considered comparing North American and IEC standards in terms of safety to identify a clear selection of such features. Ultimately, this paper provides the guidance for those contemplating this expensive design when one could seemingly select and apply the right Ex nA motors for the right application and right location without such features.

The authors discuss the importance of such features in Ex nA motors with respect to the present and most up-todate International Electrotechnical Commission (IEC) 60079-15 [9] standard of Ex nA motors. At the same time, various applications, associated risks, and the proper selection of this expensive large motor feature are discussed.The different aspects of design and application are considered, comparing the North American and IEC standards in terms of safety to identify a clear selection of such features. Ultimately, this article provides guidance for those who are considering implementing this expensive design when they could seemingly select and apply the right Ex nA motors for the right application and location without such features.

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