Lifetime of Gas Turbines Hot Section Parts in an O&G Environment

TutorialThe main driver to define the time between overhauls of a gas turbine is the life of the hot components. For an Oil&Gas operator, a turbine overhaul represents a major cost and therefore is a key point for performance improvement. This paper reviews the main damaging mechanisms of the hot sections of gas turbines, the available models, and provides orders of magnitudes of the impact of the different factors in the life of components. It also presents the operational experience of Total through cases for which the time between overhauls was successfully extended

Lifetime of Gas Turbines Hot Section Parts in an O&G Environment

TutorialThe main driver to define the time between overhauls of a gas turbine is the life of the hot components. For an Oil&Gas operator, a turbine overhaul represents a major cost and therefore is a key point for performance improvement. This paper reviews the main damaging mechanisms of the hot sections of gas turbines, the available models, and provides orders of magnitudes of the impact of the different factors in the life of components. It also presents the operational experience of Total through cases for which the time between overhauls was successfully extended

Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses

Acoustic signals generated by filamentation of ultrashort TW laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.Comment: 9 pages, 12 figure

Inquiéter le visible. À propos de Comment on freine ? de Violaine Schwartz

C’est dans un contexte de mondialisation, à la consommation débridée et frénétique, que la dramaturge Violaine Schwartz choisit dans sa pièce Comment on freine ? d’explorer et de questionner le motif du vêtement. Point de contact entre deux mondes, supposés ne jamais se rencontrer, le vêtement relie l’histoire individuelle d’une femme, sortie du coma après un accident de voiture, et l’accident de Dacca, survenu le 24 avril 2013, dans l’usine textile Rana Plaza au Bangladesh. Inscrit au sein d’un circuit globalisé et en perpétuel mouvement, le vêtement est une marchandise importée et exportée qui joue un rôle central dans la pratique des échanges internationaux. Interface du visible et de l’invisible, du voilé/dévoilé, le vêtement endosse un double rôle: celui d’objet de production et de consommation mais aussi celui d’affection.Notre article propose d’analyser comment l’espace scénographique s’élabore à partir d’évocations visuelles et sonores; comment il se transforme en un espace déréalisé susceptible de figurer les mécanismes du rêve et l’espace psychique du personnage féminin. Par-delà la construction dramaturgique d’espace-temps différents, d’ombre et de lumière, nous cherchons à révéler comment l’entrelacement et le tissage stylistique de la langue rendent possible cet entremêlement et cette confusion temporelle. Enfin, par l’intermédiaire du vêtement, notre analyse souhaite rendre lisible le surgissement du politique et l’impact du réel au sein de l’histoire individuelle à travers la trajectoire du vêtement

How lipids contribute to autophagosome biogenesis, a critical process in plant responses to stresses

Throughout their life cycle, plants face a tremendous number of environmental and developmental stresses. To respond to these different constraints, they have developed a set of refined intracellular systems including autophagy. This pathway, highly conserved among eukaryotes, is induced by a wide range of biotic and abiotic stresses upon which it mediates the degradation and recycling of cytoplasmic material. Central to autophagy is the formation of highly specialized double membrane vesicles called autophagosomes which select, engulf, and traffic cargo to the lytic vacuole for degradation. The biogenesis of these structures requires a series of membrane remodeling events during which both the quantity and quality of lipids are critical to sustain autophagy activity. This review highlights our knowledge, and raises current questions, regarding the mechanism of autophagy, and its induction and regulation upon environmental stresses with a particular focus on the fundamental contribution of lipids. How autophagy regulates metabolism and the recycling of resources, including lipids, to promote plant acclimation and resistance to stresses is further discussed

Autophagy

In plants, macroautophagy/autophagy is a key mechanism that contributes to their ability to cope with a wide range of environmental constraints such as drought, nutrient starvation or pathogen resistance. Nevertheless, the molecular mechanisms of plant autophagy, and notably that of autophagosome formation, remain poorly understood. As the starting point of our recent paper, we considered the potential functional contribution of lipids in the numerous membrane-remodeling steps involved in this process. By combining biochemistry, genetics, cell biology and high-resolution 3D imaging, we unraveled the function of the lipid phosphatidylinositol-4-phosphate (PtdIns4P) in autophagy in thus providing novel insights into the assembly of autophagosomes in plant cells.European Union’s Horizon 2020 research and innovation programm

SETD2 transcriptional control of ATG14L/S isoforms regulates autophagosome-lysosome fusion

Macroautophagy/autophagy is an evolutionarily conserved and tightly regulated catabolic process involved in the maintenance of cellular homeostasis whose dysregulation is implicated in several pathological processes. Autophagy begins with the formation of phagophores that engulf cytoplasmic cargo and mature into double-membrane autophagosomes; the latter fuse with lysosomes/vacuoles for cargo degradation and recycling. Here, we report that yeast Set2, a histone lysine methyltransferase, and its mammalian homolog, SETD2, both act as positive transcriptional regulators of autophagy. However, whereas Set2 regulates the expression of several autophagy-related (Atg) genes upon nitrogen starvation, SETD2 effects in mammals were found to be more restricted. In fact, SETD2 appears to primarily regulate the differential expression of protein isoforms encoded by the ATG14 gene. SETD2 promotes the expression of a long ATG14 isoform, ATG14L, that contains an N-terminal cysteine repeats domain, essential for the efficient fusion of the autophagosome with the lysosome, that is absent in the short ATG14 isoform, ATG14S. Accordingly, SETD2 loss of function decreases autophagic flux, as well as the turnover of aggregation-prone proteins such as mutant HTT (huntingtin) leading to increased cellular toxicity. Hence, our findings bring evidence to the emerging concept that the production of autophagy-related protein isoforms can differentially affect core autophagy machinery bringing an additional level of complexity to the regulation of this biological process in more complex organisms.Peer reviewe

Impact of BRAFV600E mutation on aggressiveness and outcomes in adult clonal histiocytosis

Histiocytoses encompass a wide spectrum of diseases, all characterized by tissue infiltration by CD68+ histiocytes. Most adult histiocytoses are considered clonal diseases because they highlight recurrent somatic mutations in the MAP-kinase pathway gene, primarily BRAF. The presence of BRAF mutation is associated with widespread disease in children with Langerhans cell histiocytosis (LCH) or cardiovascular/neurological involvement in Erdheim–Chester disease (ECD). Nevertheless, few data are available on adult clonal histiocytosis. This is why we have conducted a retrospective study of all patients with clonal histiocytosis in our institution and present the data according to the presence of BRAF mutation. Among 27 adult patients (10 ECD, 10 LCH, 5 Rosai–Dorfman disease (RDD), and 3 mixed ECD/LCH), 11 (39%) have BRAF mutation with gain of function (n = 9) and deletion (n = 2). Those patients had frequent multicentric disease with risk organ involvement, especially the brain and cardiovascular system. They had frequent associated myeloid neoplasms (mostly chronic myelomonocytic leukemia) and received more frequently targeted therapy as the front-line therapy. Nevertheless, its presence did not affect the overall survival or relapse-free survival probably due to the emergence of efficient therapies. To conclude, rapid and accurate molecular establishment in adult clonal histiocytoses is crucial because BRAFV600E mutation correlates with multicentric disease with organ involvement and incomplete metabolic response

Sensitization to the conditioned rewarding effects of morphine modulates gene expression in rat hippocampus.

Opiates addiction is characterized by its long-term persistence. In order to study the enduring changes in long-term memory in hippocampus, a pivotal region for this process, we used suppression subtractive hybridization to compare hippocampal gene expression in morphine and saline-treated rats. Animals were subjected to an extended place preference paradigm consisting of four conditioning phases. Sensitization to the reinforcing effects of the drug occurred after three conditioning phases. After 25 days of treatment rats were euthanized and the complementary DNA (cDNA) from the hippocampus of morphine-dependent and saline-treated animals were then screened for differentially expressed cDNAs. The selected 177 clones were then subjected to a microarray procedure and 20 clones were found differentially regulated. The pattern of regulated genes suggests impairments in neurotransmitter release and the activation of neuroprotective pathways

The cumate gene-switch: a system for regulated expression in mammalian cells

BACKGROUND: A number of expression systems have been developed where transgene expression can be regulated. They all have specific characteristics making them more suitable for certain applications than for others. Since some applications require the regulation of several genes, there is a need for a variety of independent yet compatible systems. RESULTS: We have used the regulatory mechanisms of bacterial operons (cmt and cym) to regulate gene expression in mammalian cells using three different strategies. In the repressor configuration, regulation is mediated by the binding of the repressor (CymR) to the operator site (CuO), placed downstream of a strong constitutive promoter. Addition of cumate, a small molecule, relieves the repression. In the transactivator configuration, a chimaeric transactivator (cTA) protein, formed by the fusion of CymR with the activation domain of VP16, is able to activate transcription when bound to multiple copies of CuO, placed upstream of the CMV minimal promoter. Cumate addition abrogates DNA binding and therefore transactivation by cTA. Finally, an adenoviral library of cTA mutants was screened to identify a reverse cumate activator (rcTA), which activates transcription in the presence rather than the absence of cumate. CONCLUSION: We report the generation of a new versatile inducible expression system