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5. VACUUM CARBURIZATION OF A TRANSMISSION SHAFT: Tests conducted on vacuum carburized and quenched shafts identify variables that increase distortion and the magnitude of residual stresses

Author

Delgado-Lopez, M. A., Colas, R., and Esteve, V.

Subjects
Specialty metals industry, Oxidation-reduction reactions, Power (Philosophy), Engineering and manufacturing industries, Science and technology
Abstract

In light and heavy transport vehicles, power from the engine to differential gears is transmitted by axisymmetric shafts. These components are subjected to fatigue under torsional or flexural conditions, and [...]

Published
2020

22. Polyunsaturated fatty acids modify the extracellular vesicle membranes and increase the production of proresolving lipid mediators of human mesenchymal stromal cells

Author

Holopainen, M. (Minna), Colas, R. A. (Romain A.), Valkonen, S. (Sami), Tigistu-Sahle, F. (Feven), Hyvärinen, K. (Kati), Mazzacuva, F. (Francesca), Lehenkari, P. (Petri), Käkelä, R. (Reijo), Dalli, J. (Jesmond), Kerkelä, E. (Erja), Laitinen, S. (Saara), Holopainen, M. (Minna), Colas, R. A. (Romain A.), Valkonen, S. (Sami), Tigistu-Sahle, F. (Feven), Hyvärinen, K. (Kati), Mazzacuva, F. (Francesca), Lehenkari, P. (Petri), Käkelä, R. (Reijo), Dalli, J. (Jesmond), Kerkelä, E. (Erja), and Laitinen, S. (Saara)

Abstract

Human mesenchymal stromal/stem cells (hMSCs) are used in experimental cell therapy to treat various immunological disorders, and the extracellular vesicles (hMSC-EVs) they produce have emerged as an option for cell-free therapeutics. The immunomodulatory function of hMSCs resembles the resolution of inflammation, in which proresolving lipid mediators (LMs) play key roles. Multiple mechanisms underlying the hMSC immunosuppressive effect has been elucidated; however, the impact of LMs and EVs in the resolution is poorly understood. In this study, we supplemented hMSCs with polyunsaturated fatty acids (PUFAs); arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, which serve as precursors for multiple LMs. We then determined the consequent compositional modifications in the fatty acid, phospholipid, and LM profiles. Mass spectrometric analyses revealed that the supplemented PUFAs were incorporated into the main membrane phospholipid classes with different dynamics, with phosphatidylcholine serving as the first acceptor. Most importantly, the PUFA modifications were transferred into hMSC-EVs, which are known to mediate hMSC immunomodulation. Furthermore, the membrane-incorporated PUFAs influenced the LM profile by increasing the production of downstream prostaglandin E2 and proresolving LMs, including Resolvin E2 and Resolvin D6. The production of LMs was further enhanced by a highly proinflammatory stimulus, which resulted in an increase in a number of mediators, most notably prostaglandins, while other stimulatory conditions had less a pronounced impact after a 48-h incubation. The current findings suggest that PUFA manipulations of hMSCs exert significant immunomodulatory effects via EVs and proresolving LMs, the composition of which can be modified to potentiate the therapeutic impact of hMSCs.

Published
2019

25. Sols artificialisés et processus d'artificialisation des sols : déterminants, impacts et leviers d'action

Author

Béchet, B., Yves Le Bissonnais, Anne Ruas, Anne Aguilera, André, M., Hervé Andrieu, Ay, S., Baumont, C., Barbe, E., Laure Vidal Beaudet, Leslie Belton-Chevallier, Berthier, E., Philippe Billet, Olivier Bonin, Jean Cavailhes, Chancibault, K., Cohen, M., Thomas Coisnon, Colas, R., Cornu, S., Jacques Cortet, Laetitia Dablanc, Darly, S., Delolme, C., Fack, G., Fromin, N., Sébastien Gadal, Benoit Gauvreau, Ghislain Geniaux, Gilli, F., Guelton, S., Guérois, M., Hedde, M., Thomas Houet, Humbertclaude, S., Laurence Jolivet, Catherine Keller, Iwan Leberre, Pierre Madec, Clément Mallet, Pauline Marty, Catherine Mering, Marjorie Musy, Walid Oueslati, Sonia, Mario Polèse, Denise Pumain, Anne Puissant, Stéphane Riou, Fabrice Rodriguez, Véronique Ruban, Julien Salanié, Christophe Schwartz, Aurélie Sotura, Mariane Thébert, Thomas Thévenin, Jacques Thisse, Alan Vergnes, Weber Christiane, Caty Werey, Maylis Desrousseaux, Unité de Recherche Environnement Physique de la plante Horticole (EPHOR), AGROCAMPUS OUEST-Université d'Angers (UA), Structures et Marché Agricoles, Ressources et Territoires (SMART), AGROCAMPUS OUEST-Institut National de la Recherche Agronomique (INRA), Aix Marseille Université (AMU), Études des Structures, des Processus d’Adaptation et des Changements de l’Espace (ESPACE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Avignon Université (AU)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Rennes), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-Université de Nantes (UN)-École pratique des hautes études (EPHE)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences et Technologies de l'Information Géographique (LaSTIG), École nationale des sciences géographiques (ENSG), Institut National de l'Information Géographique et Forestière [IGN] (IGN)-Institut National de l'Information Géographique et Forestière [IGN] (IGN), Institut de Recherche en Sciences et Techniques de la Ville (IRSTV), Université d'Angers (UA)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Université de La Rochelle (ULR)-EC. ARCHIT. NANTES-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Equipe-projet BPE (Cerema Equipe-projet BPE), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Groupe d'analyse et de théorie économique (GATE Lyon Saint-Étienne), École normale supérieure - Lyon (ENS Lyon)-Université Lumière - Lyon 2 (UL2)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Théoriser et modéliser pour aménager (UMR 6049) (ThéMA), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), INRA, ESCo Artificialisation des sols, Unité de Recherche Environnement Physique de la plante Horticole ( EPHOR ), Université d'Angers ( UA ) -AGROCAMPUS OUEST, Structures et Marché Agricoles, Ressources et Territoires ( SMART ), Institut National de la Recherche Agronomique ( INRA ) -AGROCAMPUS OUEST, Aix Marseille Université ( AMU ), Études des Structures, des Processus d’Adaptation et des Changements de l’Espace ( ESPACE ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Université d'Avignon et des Pays de Vaucluse ( UAPV ) -Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ), Littoral, Environnement, Télédétection, Géomatique ( LETG - Rennes ), Littoral, Environnement, Télédétection, Géomatique ( LETG ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Université d'Angers ( UA ) -Université de Nantes ( UN ) -École pratique des hautes études ( EPHE ) -Université de Brest ( UBO ) -Université de Rennes 2 ( UR2 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Caen Normandie ( UNICAEN ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Direction Ouest ( Cerema Direction Ouest ), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement ( Cerema ), Institut de Recherche en Sciences et Techniques de la Ville ( IRSTV ), Université d'Angers ( UA ) -Université de Nantes ( UN ) -École Centrale de Nantes ( ECN ) -Université de La Rochelle ( ULR ) -EC. ARCHIT. NANTES-Centre National de la Recherche Scientifique ( CNRS ), Groupe d'analyse et de théorie économique ( GATE Lyon Saint-Étienne ), École normale supérieure - Lyon ( ENS Lyon ) -Université Lumière - Lyon 2 ( UL2 ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Université Jean Monnet [Saint-Étienne] ( UJM ) -Centre National de la Recherche Scientifique ( CNRS ), Théoriser et modéliser pour aménager ( ThéMA ), and Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC )

Subjects
Processus, Politique et actions, [SHS.STAT]Humanities and Social Sciences/Methods and statistics, Impacts, Artificialisation des sols, Urbanisation, France, [SHS.GEO]Humanities and Social Sciences/Geography, Mesures, [ SHS.STAT ] Humanities and Social Sciences/Methods and statistics, Déterminants, [ SHS.GEO ] Humanities and Social Sciences/Geography
Published
2017

30. On the use of Earth Observation to support estimates of national greenhouse gas emissions and sinks for the Global stocktake process: lessons learned from ESA-CCI RECCAP2

Author

Ana Bastos, Philippe Ciais, Stephen Sitch, Luiz E. O. C. Aragão, Frédéric Chevallier, Dominic Fawcett, Thais M. Rosan, Marielle Saunois, Dirk Günther, Lucia Perugini, Colas Robert, Zhu Deng, Julia Pongratz, Raphael Ganzenmüller, Richard Fuchs, Karina Winkler, Sönke Zaehle, and Clément Albergel

Subjects
Paris agreement, Greenhouse gases, Carbon dioxide, Methane, Land-use change, Earth observation, Environmental sciences, GE1-350
Abstract

Abstract The Global Stocktake (GST), implemented by the Paris Agreement, requires rapid developments in the capabilities to quantify annual greenhouse gas (GHG) emissions and removals consistently from the global to the national scale and improvements to national GHG inventories. In particular, new capabilities are needed for accurate attribution of sources and sinks and their trends to natural and anthropogenic processes. On the one hand, this is still a major challenge as national GHG inventories follow globally harmonized methodologies based on the guidelines established by the Intergovernmental Panel on Climate Change, but these can be implemented differently for individual countries. Moreover, in many countries the capability to systematically produce detailed and annually updated GHG inventories is still lacking. On the other hand, spatially-explicit datasets quantifying sources and sinks of carbon dioxide, methane and nitrous oxide emissions from Earth Observations (EO) are still limited by many sources of uncertainty. While national GHG inventories follow diverse methodologies depending on the availability of activity data in the different countries, the proposed comparison with EO-based estimates can help improve our understanding of the comparability of the estimates published by the different countries. Indeed, EO networks and satellite platforms have seen a massive expansion in the past decade, now covering a wide range of essential climate variables and offering high potential to improve the quantification of global and regional GHG budgets and advance process understanding. Yet, there is no EO data that quantifies greenhouse gas fluxes directly, rather there are observations of variables or proxies that can be transformed into fluxes using models. Here, we report results and lessons from the ESA-CCI RECCAP2 project, whose goal was to engage with National Inventory Agencies to improve understanding about the methods used by each community to estimate sources and sinks of GHGs and to evaluate the potential for satellite and in-situ EO to improve national GHG estimates. Based on this dialogue and recent studies, we discuss the potential of EO approaches to provide estimates of GHG budgets that can be compared with those of national GHG inventories. We outline a roadmap for implementation of an EO carbon-monitoring program that can contribute to the Paris Agreement.

Published
2022
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33. Modifiable risk factors associated with prediabetes in men and women: A cross-sectional analysis of the cohort study in primary health care on the evolution of patients with prediabetes

Author

Díaz-Redondo, A., Giráldez-García, C., Carrillo, L., Serrano, R., García-Soidán, F.J., Artola, S., Franch, J., Díez, J., Ezkurra, P., Millaruelo, J.M., Seguí, M., Sangrós, J., Martínez-Candela, J., Muñoz, P., Goday, A., Regidor, E., Alonso, M., Álvarez, B., Álvarez, F., Álvarez, J.C., Antón, J.J., Armengol, O., Ávila, L., Babace, C., Barutell, L., Bedoya, M.J., Benito, B., Bilbeny, B., Birules, M., Blanco, C., Bobé, M.I., Boente, C., Borras, A., Bosch, R., Brito, M.J., Buil, P., Cabré, J.J., Carbonell, F., Carramiñana, F., Casorrán, A., Colas, R., Cordero, B., Cos, X., Cuatrecasas, G., De Castro, C., Flor, De La, Sen, De La, De Miguel, R.M., De Santiago, A.M., Del Castillo, M., Domínguez, D., Durán, C., Ferreiro, M., Gamarra, J., García, F., García-Giralda, L., Gijón, M.T., Gómez, Á., Gómez, M.C., González, J.C., González, M., Granero, E., Gutiérrez, A.T., Gutiérrez, F., Gutiérrez, L., Gutiérrez, M.A., Hernández, A.M., Ibáñez, M., Iglesias, R., Igual, D., Jurado, A., Llanes, R., López, F., López, R., Lorenzo, A., Losada, C., Macía, R., Magallón, R., Malo, F., Mancera, J., Mansilla, M.J., Marín, M.T., Martínez, F.J., Martín, J.L., Martínez, M.C., Martínez, R., Massana, A., Mata, M., Mayayo, M.S., Mediavilla, J.J., Mendo, L., Monzón, A., Moreno, A., Mundet, X., Mur, T., Navarro, E., Navarro, J., Nogales, P., Obaya, J.C., Oria, C., Ortega, F.J., Paniagua, F., Pardo, J.L., Pérez, F.C., Pérez, P.P., Piulats, N., Plana, R., Porta, N., Poveda, S., and Prieto

Abstract

Background: Prediabetes is a high-risk state for diabetes development, but little is known about the factors associated with this state. The aim of the study was to identify modifiable risk factors associated with the presence of prediabetes in men and women. Methods: Cohort Study in Primary Health Care on the Evolution of Patients with Prediabetes (PREDAPS-Study) is a prospective study on a cohort of 1184 subjects with prediabetes and another cohort of 838 subjects without glucose metabolism disorders. It is being conducted by 125 general practitioners in Spain. Data for this analysis were collected during the baseline stage in 2012. The modifiable risk factors included were: smoking habit, alcohol consumption, low physical activity, inadequate diet, hypertension, dyslipidemia, and obesity. To assess independent association between each factor and prediabetes, odds ratios (ORs) were estimated using logistic regression models. Results: Abdominal obesity, low plasma levels of high-density lipoprotein cholesterol (HDL-cholesterol), and hypertension were independently associated with the presence of prediabetes in both men and women. After adjusting for all factors, the respective ORs (95% Confidence Intervals) were 1.98 (1.41-2.79), 1.88 (1.23-2.88) and 1.86 (1.39-2.51) for men, and 1.89 (1.36-2.62), 1.58 (1.12-2.23) and 1.44 (1.07-1.92) for women. Also, general obesity was a risk factor in both sexes but did not reach statistical significance among men, after adjusting for all factors. Risky alcohol consumption was a risk factor for prediabetes in men, OR 1.49 (1.00-2.24). Conclusions: Obesity, low HDL-cholesterol levels, and hypertension were modifiable risk factors independently related to the presence of prediabetes in both sexes. The magnitudes of the associations were stronger for men than women. Abdominal obesity in both men and women displayed the strongest association with prediabetes. The findings suggest that there are some differences between men and women, which should be taken into account when implementing specific recommendations to prevent or delay the onset of diabetes in adult population.

Published
2015

34. Space-based Earth observation in support of the UNFCCC Paris Agreement

Author

Michaela I. Hegglin, Ana Bastos, Heinrich Bovensmann, Michael Buchwitz, Dominic Fawcett, Darren Ghent, Gemma Kulk, Shubha Sathyendranath, Theodore G. Shepherd, Shaun Quegan, Regine Röthlisberger, Stephen Briggs, Carlo Buontempo, Anny Cazenave, Emilio Chuvieco, Philippe Ciais, David Crisp, Richard Engelen, Suvarna Fadnavis, Martin Herold, Martin Horwath, Oskar Jonsson, Gabriel Kpaka, Christopher J. Merchant, Christian Mielke, Thomas Nagler, Frank Paul, Thomas Popp, Tristan Quaife, Nick A. Rayner, Colas Robert, Marc Schröder, Stephen Sitch, Sara Venturini, Robin van der Schalie, Mendy van der Vliet, Jean-Pierre Wigneron, and R. Iestyn Woolway

Subjects
climate change, Earth observation, Paris Agreement, enhanced transparency framework, mitigation, adaptation, Environmental sciences, GE1-350
Abstract

Space-based Earth observation (EO), in the form of long-term climate data records, has been crucial in the monitoring and quantification of slow changes in the climate system—from accumulating greenhouse gases (GHGs) in the atmosphere, increasing surface temperatures, and melting sea-ice, glaciers and ice sheets, to rising sea-level. In addition to documenting a changing climate, EO is needed for effective policy making, implementation and monitoring, and ultimately to measure progress and achievements towards the overarching goals of the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement to combat climate change. The best approach for translating EO into actionable information for policymakers and other stakeholders is, however, far from clear. For example, climate change is now self-evident through increasingly intense and frequent extreme events—heatwaves, droughts, wildfires, and flooding—costing human lives and significant economic damage, even though single events do not constitute “climate”. EO can capture and visualize the impacts of such events in single images, and thus help quantify and ultimately manage them within the framework of the UNFCCC Paris Agreement, both at the national level (via the Enhanced Transparency Framework) and global level (via the Global Stocktake). We present a transdisciplinary perspective, across policy and science, and also theory and practice, that sheds light on the potential of EO to inform mitigation, including sinks and reservoirs of greenhouse gases, and adaptation, including loss and damage. Yet to be successful with this new mandate, EO science must undergo a radical overhaul: it must become more user-oriented, collaborative, and transdisciplinary; span the range from fiducial to contextual data; and embrace new technologies for data analysis (e.g., artificial intelligence). Only this will allow the creation of the knowledge base and actionable climate information needed to guide the UNFCCC Paris Agreement to a just and equitable success.

Published
2022
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35. On the Challenge of Plasma Heating with the JET Metallic Wall

Author

Mayoral, M., Bobkov, V., Czarnecka, A., Day, I., Ekedahl, A., Jacquet, P., Goniche, M., King, R., Kirov, K., Lerche, E., Mailloux, J., Van Eester, D., Asunta, O., Challis, C., Ciric, D., Coenen, J., Colas, R., Giroud, M., Graham, M., Jenkins, I., Joffrin, E., Jones, T., King, D., Kiptily, V., Klepper, C., Maggi, C., Marcotte, F., Matthews, G., Milanesio, D., Monakhov, I., Nightingale, M., Neu, R., Ongena, J., Pütterich, T., Riccardo, V., Rimini, F., Strachan, J., Surrey, E., Thompson, V., Van Rooij, G., and JET-EFDA Contributors

Published
2013

36. Caracterización de aceros dual-phase obtenidos por laminación en caliente

Author

Monsalve G, A., Artigas A, A., Castro C, F., Colas, R., and Houbaert, Y.

Subjects
Hot-rolling, Drawing, Embutición, Laminado en caliente, Textures, Aceros, Steels, Dual-Phase, Texturas
Abstract

Samples were obtained from C-Mn-Si steel available in the market. Through a hot rolling and coiling process, it was possible to obtain Dual-Phase steel with microstructural and mechanical properties in the theoretical range typical of this material. The thermomechanical process consisted of a strong reduction by multiples pass of hot rolling at temperatures above Ar3, controlled-cooling the sheets during 5 s (at a rate of 20 °C/s in the equilibrium range α+γ. Temperature Ar3 measured by differential scanning calorimetry was 890 °C. Quenching was then carried out in the coiling temperatures range (500-675 °C), cooling the samples in accordance to an established curve that corresponds to the actual cooling curve of a coil. The microstructural characterization of the samples obtained was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, texture measurements were carried out by X-ray diffraction in order to study the resulting orientations due to the finishing rolling temperature and coiling temperature, determining the influence on these parameters of the different texture components. The microstructural results were complemented with the normal and planar anisotropy indexes measured in according to the ASTM E-517 standard. The intensities of the different texture components were correlated with the values of anisotropy indexes, finding that it is possible to obtain only a slightly enhancement in the normal anisotropy index through an appropriate combination of finish rolling and coiling temperatures. Se tomaron muestras de acero al C-Mn-Si disponible en el mercado y mediante un proceso de laminación en caliente y bobinado, se obtuvo acero Dual Phase con microestructura y propiedades mecánicas dentro del rango teórico esperado de este material. El proceso termomecánico consistió en producir una fuerte reducción a temperaturas mayores a Ar3, mediante pasadas de laminación sucesivas, para posteriormente enfriar el acero durante aproximadamente 5 s, (a una velocidad de 20 °C/s) en el rango de equilibrio α+γ. La temperatura Ar3, medida mediante calorimetría diferencial de barrido, fue de 890 °C. A continuación se realizó un temple en el rango de temperaturas de bobinado (550-675 °C), enfriando posteriormente las muestras de acuerdo a una curva pre establecida, que corresponde a la curva de enfriamiento real de una bobina. La caracterización microestructural de las muestras obtenidas, se realizó mediante microscopía óptica, microscopía electrónica de barrido y microscopía de fuerza atómica. Adicionalmente se realizó una medición de texturas mediante difracción de rayos X, para el estudio de las orientaciones resultantes, producto de la variación de la temperatura de término de laminación (TTL) y la temperatura de bobinado (TB), determinándose cómo afectan estas variables a las distintas componentes de texturas. Se complementó la información microestructural con los valores de los índices de anisotropía normal y planar, medidos de acuerdo a la norma ASTM E-517. Se correlacionaron las intensidades de las componentes de texturas encontradas con los valores de los índices de anisotropía, encontrándose que sólo es posible producir leves mejoras en el índice de anisotropía normal, a través de una combinación apropiada de las temperaturas de término de laminación y de bobinado.

Published
2011
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37. Synthesis of highpurity-SiC and-Si3 N4 from rice hulls

Author

TREVIÑO, B., GÓMEZ, I., and COLAS, R.

Subjects
Q Science (General), QD Chemistry
Abstract

Silicon carbide and silicon nitride were syntbesized from ashes obtained by heating rice hulls at 800C for 3 hours in argon. –SiC was produced from !he ashes by reheating tbem al 1400C fOl 8 hours in argon. whereas –S3N4. was obtained by heating tbe ashes al temperatures ranging from 1250C to 1400C for perlods of 3 to 6 hours in a nitrogen rich atmospbere. The products were characterized by infrared spectrosropy. X-ray aod scanning electro. microscopy. High purity -SiC aod –S3N4. compounds witb whiskertype m.orpbology were obtained. Itwas possible to obtain –S3N4 with.out SiC by heating the ashes for 6 hours at 125OC.

Published
2011

47. Aging of a Low Carbon Heat Resistant Cast Alloy

Author

Sustaita-Torres Ireri A., Haro-Rodríguez Sergio, and Colás Rafael

Subjects
heat-resisting cast alloys, precipitation, aging, microstructural evolution, Technology, Chemical technology, TP1-1185, Chemicals: Manufacture, use, etc., TP200-248
Abstract

The changes in microstructure that take place during aging a low carbon heat resistant alloy at 750°C for a period of time of up to 1,000 h were studied by optical and scanning electron microscopy, X-ray diffraction and mechanical testing. The microstructure of the as-cast alloy consisted of an austenitic matrix and a network of Nb- and Cr-rich primary carbides that were identified by their tonality when viewed in backscattered mode in a scanning electron microscopy. Aging promotes precipitation of secondary carbides and the transformation of the Nb-rich particles. The mechanical properties are affected by the occurrence of the different phenomena.

Published
2018
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49. Depressed levels of prostaglandin F2α in mice lacking Akr1b7 increase basal adiposity and predispose to diet-induced obesity.

Author

Volat FE, Pointud JC, Pastel E, Morio B, Sion B, Hamard G, Guichardant M, Colas R, Lefrançois-Martinez AM, Martinez A, Volat, Fanny E, Pointud, Jean-Christophe, Pastel, Emilie, Morio, Béatrice, Sion, Benoit, Hamard, Ghislaine, Guichardant, Michel, Colas, Romain, Lefrançois-Martinez, Anne-Marie, and Martinez, Antoine

Abstract

Negative regulators of white adipose tissue (WAT) expansion are poorly documented in vivo. Prostaglandin F(2α) (PGF(2α)) is a potent antiadipogenic factor in cultured preadipocytes, but evidence for its involvement in physiological context is lacking. We previously reported that Akr1b7, an aldo-keto reductase enriched in adipose stromal vascular fraction but absent from mature adipocytes, has antiadipogenic properties possibly supported by PGF(2α) synthase activity. To test whether lack of Akr1b7 could influence WAT homeostasis in vivo, we generated Akr1b7(-/-) mice in 129/Sv background. Akr1b7(-/-) mice displayed excessive basal adiposity resulting from adipocyte hyperplasia/hypertrophy and exhibited greater sensitivity to diet-induced obesity. Following adipose enlargement and irrespective of the diet, they developed liver steatosis and progressive insulin resistance. Akr1b7 loss was associated with decreased PGF(2α) WAT contents. Cloprostenol (PGF(2α) agonist) administration to Akr1b7(-/-) mice normalized WAT expansion by affecting both de novo adipocyte differentiation and size. Treatment of 3T3-L1 adipocytes and Akr1b7(-/-) mice with cloprostenol suggested that decreased adipocyte size resulted from inhibition of lipogenic gene expression. Hence, Akr1b7 is a major regulator of WAT development through at least two PGF(2α)-dependent mechanisms: inhibition of adipogenesis and lipogenesis. These findings provide molecular rationale to explore the status of aldo-keto reductases in dysregulations of adipose tissue homeostasis. [ABSTRACT FROM AUTHOR]

Published
2012
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50. High Temperature Oxidation of a Work Roll Grade High-Chromium White Cast Iron

Author

Ramírez-Ramírez, J H, Colas, R, and Garza-Montes-de-Oca, N F

Abstract

High-chromium white cast iron is a common material for the manufacture of the work rolls used in the finishing stands in hot strip mills. The high temperature oxidation behaviour of as-cast and heat-treated high-chromium white cast iron was studied by gravimetric means at 650 °C in atmospheres that included dry air and a mixture of dry air and water vapour. For both environmental and material conditions, the oxidation rate of the alloys was represented by parabolic trends and the oxidation phenomenon was more obvious when the samples were oxidised in water vapour. Water vapour also influenced the chemical composition of the oxides formed in the alloy and under this condition, the oxide scale formed on the alloy contained the oxides FeCr2O4, (Fe, Cr)3O4and (Fe, Cr)2O3. In contrast, the alloys exposed to dry air conditions only experienced the formation of FeCr2O4and (Fe, Cr)2O3. It was found that the presence of water vapour and the chromium content of the alloys increased the oxidation rate by a mechanism that involved chromium depletion of the oxide as a result of hydroxide formation. The differences observed in the oxidation behaviour of the alloy are discussed in terms of the composition of the oxidant atmosphere and the metallurgical condition of the specimens.

Published
2013
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