298 research outputs found

    The stellar orbit distribution in present-day galaxies inferred from the CALIFA survey

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    Galaxy formation entails the hierarchical assembly of mass, along with the condensation of baryons and the ensuing, self-regulating star formation. The stars form a collisionless system whose orbit distribution retains dynamical memory that can constrain a galaxy's formation history. The ordered-rotation dominated orbits with near maximum circularity λz1\lambda_z \simeq1 and the random-motion dominated orbits with low circularity λz0\lambda_z \simeq0 are called kinematically cold and kinematically hot, respectively. The fraction of stars on `cold' orbits, compared to the fraction of stars on `hot' orbits, speaks directly to the quiescence or violence of the galaxies' formation histories. Here we present such orbit distributions, derived from stellar kinematic maps via orbit-based modelling for a well defined, large sample of 300 nearby galaxies. The sample, drawn from the CALIFA survey, includes the main morphological galaxy types and spans the total stellar mass range from 108.710^{8.7} to 1011.910^{11.9} solar masses. Our analysis derives the orbit-circularity distribution as a function of galaxy mass, p(λz  M)p(\lambda_z~|~M_\star), and its volume-averaged total distribution, p(λz)p(\lambda_z). We find that across most of the considered mass range and across morphological types, there are more stars on `warm' orbits defined as 0.25λz0.80.25\le \lambda_z \le 0.8 than on either `cold' or `hot' orbits. This orbit-based "Hubble diagram" provides a benchmark for galaxy formation simulations in a cosmological context

    Mechanical properties of double-layer and graded composite coatings of YSZ obtained by atmospheric plasma spraying

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    Double-layer and graded composite coatings of yttria-stabilized zirconia were sprayed on metallic substrates by atmospheric plasma spray. The coating architecture was built up by combining two different feedstocks: one micro- and one nanostructured. Microstructural features and mechanical properties (hardness and elastic modulus) of the coatings were determined by FE-SEM microscopy and nanoindentation technique, respectively. Additional adherence and scratch tests were carried out in order to assess the failure mechanisms occurring between the layers comprising the composites. Microstructural inspection of the coatings confirms the two-zone microstructure. This bimodal microstructure which is exclusive of the layer obtained from the nanostructured feedstock negatively affects the mechanical properties of the whole composite. Nanoindentation tests suitably reproduce the evolution of mechanical properties through coatings thickness on the basis of the position and/or amount of nanostructured feedstock used in the depositing layer. Adhesion and scratch tests show the negative effect on the coating adhesion of layer obtained from the nanostructured feedstock when this layer is deposited on the bond coat. Thus, the poor integrity of this layer results in lower normal stresses required to delaminate the coating in the adhesion test as well as minor critical load registered by using the scratch test.This work has been supported by the Spanish Ministry of Science and Innovation (Project MAT2012-38364-C03) and co-funded by ERDF (European Regional Development Funds).Carpio-Cobo, P.; Rayón Encinas, E.; Salvador Moya, MD.; Lusvarghi, L.; Sanchez, E. (2016). Mechanical properties of double-layer and graded composite coatings of YSZ obtained by atmospheric plasma spraying. Journal of Thermal Spray Technology. 25(4):778-787. https://doi.org/10.1007/s11666-016-0390-zS778787254Y.S. Tian, C.Z. Chen, D.Y. Wang, and J.I. Quianmao, Recent Developments in Zirconia Thermal Barrier Coatings, Surf. Rev. Lett., 2005, 12, p 369-378S. Sampath, U. Schulz, M.O. Jarligo, and S. Kuroda, Processing Science of Advanced Thermal-Barrier Systems, MRS Bull., 2012, 37(10), p 903-910D.R. Clarke, M. Oeschsner, and N.P. Padture, Thermal-Barrier Coatings for More Efficient Gas-Turbine Engines, MRS Bull., 2012, 37(10), p 891-898A. Feuersein, J. Knapp, T. Taylor, A. Ashary, A. Bolcavage, and N. Hitchman, Technical and Economical Aspects of Current Thermal Barrier Coating Systems for Gas Turbine Engines by Thermal Spray and EBPVD: A Review, J. Therm. Spray Technol., 2008, 17(2), p 199-213R.S. Lima and B.R. Marple, Thermal Spray Coatings Engineered from Nanostructured Ceramic Agglomerated Powders for Structural, Thermal Barrier and Biomedical Applications: A Review, J. Therm. Spray Technol., 2007, 16(1), p 40-63P. Fauchais, G. Montavon, R.S. Lima, and B.R. Marple, Engineering a New Class of Thermal Spray Nano-based Microstructures from Agglomerated Nanostructured Particles, Suspensions and Solutions: An Invited Review, J. Phys. D Appl. Phys., 2011, 44(9), p 093001P. Carpio, Q. Blochet, B. Pateyron, L. Pawlowski, M.D. Salvador, A. Borrell, and E. Sánchez, Correlation of Thermal Conductivity of Suspension Plasma Sprayed Yttira Stabilized Zirconia Coatings with some Microstructural Effects, Mater. Lett., 2013, 107, p 370-373R. Vassen, A. Stuke, and D. Stöver, Recent Developments in the Field of Thermal Barrier Coatings, J. Therm. Spray Technol., 2009, 18(2), p 181-186H. Dai, X. Zhong, J. Li, Y. Zhang, J. Meng, and X. Cao, Thermal Stability of Double-Ceramic-Layer Thermal Barrier Coatings with Various Coating Thickness, Mater. Sci. Eng. A—Struct., 2006, 433(1), p 1–7V. Viswanathan, G. Dwivedi, and S. Sampath, Multimaterial Thermal Barrier Coating Systems: Design, Synthesis, and Performance Assessment, J. Am. Ceram. Soc., 2015, 98(6), p 1769-1777M. Saremi and Z. Valefi, Thermal and Mechanical Properties of Nano-YSZ-Alumina Functionally Graded Coatings Deposited by Nano-agglomerated Powder Plasma Spraying, Ceram. Int., 2014, 40(8), p 13453-13459A. Portinham, V. Teixeira, J. Carneiro, J. Martins, M.F. Costa, R. Vassen, and D. Stoever, Characterization of Thermal Barrier Coatings with a Gradient Porosity, Surf. Coat. Technol., 2005, 195(2), p 245-251P. Carpio, E. Bannier, M.D. Salvador, R. Benavente, and E. Sánchez, Multilayer and Particle Size-Graded YSZ Coatings Obtained by Plasma Spraying of Micro- and Nanostructured Feedstocks, J. Therm. Spray Technol., 2014, 23(8), p 1362-1372S. Nath, I. Manna, and J.D. Majumdar, Nanomechanical Behavior of Yttria Stabilized Zirconia (YSZ) Based Thermal Barrier Coating, Ceram. Int., 2015, 41(4), p 5247-5256P. Carpio, E. Rayón, L. Pawlowski, A. Cattini, R. Benavente, E. Bannier, M.D. Salvador, and E. Sánchez, Microstructure and Indentation Mechanical Properties of YSZ Nanostructured Coatings Obtained by Suspension Plasma Spraying, Surf. Coat. Technol., 2013, 220, p 237-243H.B. Guo, H. Murakami, and S. Kuroda, Effect of Hollow Spherical Powder Size Distribution on Porosity and Segmentation Cracks in Thermal Barrier Coatings, J. Am. Ceram. Soc., 2006, 89(12), p 3797-3804R.S. Lima, A. Kucuk, and C.C. Berndt, Integrity of Nanostructured Partially Stabilized Zirconia After Plasma Spray Processing, Mater. Sci. Eng. A, 2001, 313(1), p 75-82E. Rayón, V. Bonache, M.D. Salvador, and E. Sánchez, Hardness and Young’s Modulus Distributions in Atmospheric Plasma Sprayed WC-Co Coatings Using Nanoindentation, Surf. Coat. Technol., 2011, 205(17), p 4192-4197J.A. Wollmershauser, B.N. Feigelson, E.P. Gorzkowski, C.T. Ellis, R. Goswami, S.B. Qadri, J.G. Tischler, F.J. Kub, and R.K. Everett, An Extend Hardness Limit in Bulk Nanoceramics, Acta Mater., 2014, 69, p 9-16L. Wang, Y. Wang, X.G. Sun, J.Q. He, Z.Y. Pan, and C.H. Wang, Microstructure and Indentation Mechanical Properties of Plasma Sprayed Nano-Bimodal and Conventional ZrO2-8 wt% Y2O3 Thermal Barrier Coatings, Vacuum, 2012, 86(8), p 1174-1185G.S. Barroso, W. Krenkel, and G. Motz, Low Thermal Conductivity Coating System for Application up to 1000 °C by Simple PDC Processing with Active and Passive Fillers, J. Eur. Ceram. Soc., 2015, 35(12), p 3339-3348R. Ghasemi, R. Shoja-Razavi, R. Mozafarinia, H. Jamali, M. Hajizadh-Oghaz, and R. Ahmadi-Pidani, The Influence of Laser Treatment on Hot Corrosion Behavior of Plasma-Sprayed Nanostructured Yttria Stabilized Zirconia Thermal Barrier Coatings, J. Eur. Ceram. Soc., 2014, 34(8), p 2013-2021E. Rayón, V. Bonache, M.D. Salvador, E. Bannier, E. Sánchez, A. Denoirjean, and H. Ageorges, Nanoindentation Study of the Mechanical and Damage Behaviour of Suspension Plasma Sprayed TiO2 Coatings, Surf. Coat. Technol., 2012, 206(10), p 2655-2660J.J. Roa, E. Jiménez-Piqué, R. Martínez, G. Ramírez, J.M. Tarragó, R. Rodríguez, and L. Llanes, Contact Damage and Fracture Micromechanisms of Multilayered TiN/CrN Coatings at Micro- and Nano-length Scales, Thin Solid Films, 2014, 571(2), p 308-31

    Effective Rheology of Bubbles Moving in a Capillary Tube

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    We calculate the average volumetric flux versus pressure drop of bubbles moving in a single capillary tube with varying diameter, finding a square-root relation from mapping the flow equations onto that of a driven overdamped pendulum. The calculation is based on a derivation of the equation of motion of a bubble train from considering the capillary forces and the entropy production associated with the viscous flow. We also calculate the configurational probability of the positions of the bubbles.Comment: 4 pages, 1 figur

    Education and inequality in Finland, Spain and Brazil

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    Production of INCASI Project H2020-MSCA-RISE-2015 GA 691004Finland, Spain and Brazil are three very internally complex and heterogeneous realities, with contradictions and permanent reforms to their education systems. In a first quantitative approach each country can be placed in a continuum of the education system that goes from most successful in terms of reaching a high level of education all across the population, in conditions of equity and facilitating youths' incorporation into the labour market, to least successful, with Finland and Brazil occupying either end of the spectrum respectively and Spain occupying an intermediate situation. Although there are differences, they share certain tensions in their respective education systems. On the one hand, about the conception of education, ranging from more utilitarian, human capital theories, to the more humanist and civic-minded perspective. On the other hand, the challenge of comprehensiveness between an academic and a vocational path. In addition, there is also the challenge of improving the education level of the population while also improving equality. The tensions differ from country to country, since their education traditions and cooperation and conflict strategies between the education agents, with varying levels of resources and different alliances with political actors vary, as does the social consensus

    Origin and Epidemiological History of HIV-1 CRF14_BG

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    This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Users must also make clear the license terms under which the work was published. CC BY Licence: http://creativecommons.org/licenses/by/4.0/Background: CRF14_BG isolates, originally found in Spain, are characterized by CXCR4 tropism and rapid disease progression. This study aimed to identify the origin of CRF14_BG and reconstruct its epidemiological history based on new isolates from Portugal.Methodology/Principal Findings: C2V3C3 env gene sequences were obtained from 62 samples collected in 1993–1998 from Portuguese HIV-1 patients. Full-length genomic sequences were obtained from three patients. Viral subtypes, diversity, divergence rate and positive selection were investigated by phylogenetic analysis. The molecular structure of the genomes was determined by bootscanning. A relaxed molecular clock model was used to date the origin of CRF14_BG. Geno2pheno was used to predict viral tropism. Subtype B was the most prevalent subtype (45 sequences; 73%) followed by CRF14_BG (8; 13%), G (4; 6%), F1 (2; 3%), C (2; 3%) and CRF02_AG (1; 2%). Three CRF14_BG sequences were derived from 1993 samples. Near full-length genomic sequences were strongly related to the CRF14_BG isolates from Spain. Genetic diversity of the Portuguese isolates was significantly higher than the Spanish isolates (0.044 vs 0.014, P,0.0001). The mean date of origin of the CRF14_BG cluster was estimated to be 1992 (range, 1989 and 1996) based on the subtype G genomic region and 1989 (range, 1984–1993) based on the subtype B genomic region. Most CRF14_BG strains (78.9%) were predicted to be CXCR4. Finally, up to five amino acids were under selective pressure in subtype B V3 loop whereas only one was found in the CRF14_BG cluster.Conclusions: CRF14_BG emerged in Portugal in the early 1990 s soon after the beginning of the HIV-1 epidemics, spread to Spain in late 1990 s as a consequence of IVDUs migration and then to the rest of Europe. CXCR4 tropism is a general characteristic of this CRF that may have been selected for by escape from neutralizing antibody response

    The art of cellular communication: tunneling nanotubes bridge the divide

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    The ability of cells to receive, process, and respond to information is essential for a variety of biological processes. This is true for the simplest single cell entity as it is for the highly specialized cells of multicellular organisms. In the latter, most cells do not exist as independent units, but are organized into specialized tissues. Within these functional assemblies, cells communicate with each other in different ways to coordinate physiological processes. Recently, a new type of cell-to-cell communication was discovered, based on de novo formation of membranous nanotubes between cells. These F-actin-rich structures, referred to as tunneling nanotubes (TNT), were shown to mediate membrane continuity between connected cells and facilitate the intercellular transport of various cellular components. The subsequent identification of TNT-like structures in numerous cell types revealed some structural diversity. At the same time it emerged that the direct transfer of cargo between cells is a common functional property, suggesting a general role of TNT-like structures in selective, long-range cell-to-cell communication. Due to the growing number of documented thin and long cell protrusions in tissue implicated in cell-to-cell signaling, it is intriguing to speculate that TNT-like structures also exist in vivo and participate in important physiological processes
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