The Spitzer Atlas of Stellar Spectra

We present the Spitzer Atlas of Stellar Spectra (SASS), which includes 159 stellar spectra (5 to 32 mic; R~100) taken with the Infrared Spectrograph on the Spitzer Space Telescope. This Atlas gathers representative spectra of a broad section of the Hertzsprung-Russell diagram, intended to serve as a general stellar spectral reference in the mid-infrared. It includes stars from all luminosity classes, as well as Wolf-Rayet (WR) objects. Furthermore, it includes some objects of intrinsic interest, like blue stragglers and certain pulsating variables. All the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, dominated by Hydrogen lines around A spectral types. Besides these, the most noticeable photospheric features correspond to water vapor and silicon monoxide in late-type objects and methane and ammonia features at the latest spectral types. Most supergiant spectra in the Atlas present evidence of circumstellar gas. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases PAH features. Sequences of WR stars present the well-known pattern of lines of HeI and HeII, as well as forbidden lines of ionized metals. The characteristic flat-top shape of the [Ne III] line is evident even at these low spectral resolutions. Several Luminous Blue Variables and other transition stars are present in the Atlas and show very diverse spectra, dominated by circumstellar gas and dust features. We show that the [8]-[24] Spitzer colors (IRAC and MIPS) are poor predictors of spectral type for most luminosity classes.Comment: Accepted by ApJS; Atlas contents available from: http://web.ipac.caltech.edu/staff/ardila/Atlas/index.html; http://irsa.ipac.caltech.edu/data/SPITZER/SASS/; 70 PDF pages, including figure

Genomic analysis of 48 paenibacillus larvae bacteriophages

Indexación: Scopus.Funding: Research at UNLV was funded by National Institute of General Medical Sciences grant GM103440 (NV INBRE), the UNLV School of Life Sciences, and the UNLV College of Sciences. E.C.-N. was funded by CONICYT-FONDECYT de iniciación en la investigación 11160905. Research at BYU was funded by the BYU Microbiology & Molecular Biology Department, and private donations through LDS Philanthropies.The antibiotic-resistant bacterium Paenibacillus larvae is the causative agent of American foulbrood (AFB), currently the most destructive bacterial disease in honeybees. Phages that infect P. larvae were isolated as early as the 1950s, but it is only in recent years that P. larvae phage genomes have been sequenced and annotated. In this study we analyze the genomes of all 48 currently sequenced P. larvae phage genomes and classify them into four clusters and a singleton. The majority of P. larvae phage genomes are in the 38–45 kbp range and use the cohesive ends (cos) DNA-packaging strategy, while a minority have genomes in the 50–55 kbp range that use the direct terminal repeat (DTR) DNA-packaging strategy. The DTR phages form a distinct cluster, while the cos phages form three clusters and a singleton. Putative functions were identified for about half of all phage proteins. Structural and assembly proteins are located at the front of the genome and tend to be conserved within clusters, whereas regulatory and replication proteins are located in the middle and rear of the genome and are not conserved, even within clusters. All P. larvae phage genomes contain a conserved N-acetylmuramoyl-L-alanine amidase that serves as an endolysin. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.https://www.mdpi.com/1999-4915/10/7/37

Comportamiento frente a la corrosión inducida por cloruros de armaduras de nuevos aceros inoxidables con bajo contenido en níquel

La utilización de armaduras de acero inoxidable, de los tipos austeníticos y dúplex, con el objetivo de prolongar la vida útil de las estructuras de hormigón, es una alternativa que está recibiendo cada vez más consideración. Los aceros inoxidables son aleaciones fundamentalmente de cromo y níquel, con muy alta resistencia a la corrosión, especialmente por cloruros. El elevado coste del níquel y sus grandes fluctuaciones en el mercado, han favorecido la aparición de nuevos aceros inoxidables con bajo contenido en dicha aleación y, por lo tanto, más económicos, que sin embargo presentan una resistencia a la corrosión similar a los tradicionales. En este trabajo se ha evaluado la resistencia a la corrosión por cloruros de dos nuevos aceros inoxidables de bajo contenido en níquel. Uno de los aceros es austenítico, de producción en forma de chapa, y el otro dúplex, que se comercializa como barra corrugada. La resistencia a la corrosión se ha evaluado, respectivamente, mediante ensayos electroquímicos de dichos aceros embebidos en solución simulada de poros de hormigón y en probetas de mortero contaminados con diferentes cuantías de cloruros. Los resultados de los ensayos se han comparado con los del acero austenítico tradicional AISI 304 y del acero al carbono B500SD

The Evolution of Anodic Hydrogen on High Purity Magnesium in Acidic Buffer Solution

Hydrogen evolution (HE) on anodically polarized Mg, commonly referred to as Negative Difference Effect, was studied by galvanodynamic measurements coupled with real-time gravimetric H2 volume collection, the Scanning Vibrating Electrode Technique and potentiodynamic polarization experiments. High purity Mg (99.96% Mg) electrodes were studied in chloride-free 0.1 M citric acid solution buffered at pH with the aim of determining the source of anodic HE and the role of the corrosion film on the process. In such conditions of pH, the typical dark corrosion product exhibited in neutral and alkaline solutions was not found but the HE rate still increased with increasing potential. Evidence that HE on dissolving high purity Mg is associated with the regions dominated by the anodic dissolution reaction is provided. The role of noble impurity enrichment on the electrode surface during anodic polarization and the effect of Fe re-deposition are also discussed

Influence of geometrical parameters on the linear stability of a Benard-Marangoni problem

[EN] A linear stability analysis of a thin liquid film flowing over a plate is performed. The analysis is performed in an annular domain when momentum diffusivity and thermal diffusivity are comparable (relatively low Prandtl number, Pr = 1.2). The influence of the aspect ratio (Gamma) and gravity, through the Bond number (Bo), in the linear stability of the flow are analyzed together. Two different regions in the Gamma-Bo plane have been identified. In the first one the basic state presents a linear regime (in which the temperature gradient does not change sign with r). In the second one, the flow presents a nonlinear regime, also called return flow. A great diversity of bifurcations have been found just by changing the domain depth d. The results obtained in this work are in agreement with some reported experiments, and give a deeper insight into the effect of physical parameters on bifurcations.The computations shown in this work were made possible by a generous grant of computer time from the supercomputation center of the Universitat Politecnica de Valencia.Hoyas, S.; Fajardo, P.; Pérez Quiles, MJ. (2016). Influence of geometrical parameters on the linear stability of a Benard-Marangoni problem. Physical Review E. 93(4). https://doi.org/10.1103/PhysRevE.93.043105S934Bénard, H. (1901). Les tourbillons cellulaires dans une nappe liquide. - Méthodes optiques d’observation et d’enregistrement. Journal de Physique Théorique et Appliquée, 10(1), 254-266. doi:10.1051/jphystap:0190100100025400Smith, M. K., & Davis, S. H. (1983). Instabilities of dynamic thermocapillary liquid layers. Part 1. Convective instabilities. Journal of Fluid Mechanics, 132, 119-144. doi:10.1017/s0022112083001512Garnier, N., & Chiffaudel, A. (2001). Two dimensional hydrothermal waves in an extended cylindrical vessel. The European Physical Journal B, 19(1), 87-95. doi:10.1007/s100510170352Hoyas, S., Herrero, H., & Mancho, A. M. (2002). Bifurcation diversity of dynamic thermocapillary liquid layers. Physical Review E, 66(5). doi:10.1103/physreve.66.057301Hoyas, S., Herrero, H., & Mancho, A. M. (2002). Thermal convection in a cylindrical annulus heated laterally. Journal of Physics A: Mathematical and General, 35(18), 4067-4083. doi:10.1088/0305-4470/35/18/306Hoyas, S., Mancho, A. M., Herrero, H., Garnier, N., & Chiffaudel, A. (2005). Bénard–Marangoni convection in a differentially heated cylindrical cavity. Physics of Fluids, 17(5), 054104. doi:10.1063/1.1876892Herrero, H., & Mancho, A. M. (1998). Influence of aspect ratio in convection due to nonuniform heating. Physical Review E, 57(6), 7336-7339. doi:10.1103/physreve.57.7336Mancho, A., Herrero, H., & Burguete, J. (1997). Primary instabilities in convective cells due to nonuniform heating. Physical Review E, 56(3), 2916-2923. doi:10.1103/physreve.56.2916Ezersky, A. B., Garcimartín, A., Burguete, J., Mancini, H. L., & Pérez-García, C. (1993). Hydrothermal waves in Marangoni convection in a cylindrical container. Physical Review E, 47(2), 1126-1131. doi:10.1103/physreve.47.1126Hoyas, S., Gil, A., Fajardo, P., & Pérez-Quiles, M. J. (2013). Codimension-three bifurcations in a Bénard-Marangoni problem. Physical Review E, 88(1). doi:10.1103/physreve.88.015001Peng, L., Li, Y.-R., Shi, W.-Y., & Imaishi, N. (2007). Three-dimensional thermocapillary–buoyancy flow of silicone oil in a differentially heated annular pool. International Journal of Heat and Mass Transfer, 50(5-6), 872-880. doi:10.1016/j.ijheatmasstransfer.2006.08.015Shi, W., Liu, X., Li, G., Li, Y.-R., Peng, L., Ermakov, M. K., & Imaishi, N. (2010). Thermocapillary Convection Instability in Shallow Annular Pools by Linear Stability Analysis. Journal of Superconductivity and Novel Magnetism, 23(6), 1185-1188. doi:10.1007/s10948-010-0661-8Torregrosa, A. J., Hoyas, S., Pérez-Quiles, M. J., & Mompó-Laborda, J. M. (2013). Bifurcation Diversity in an Annular Pool Heated from Below: Prandtl and Biot Numbers Effects. Communications in Computational Physics, 13(2), 428-441. doi:10.4208/cicp.090611.170212aEckert, E. R. G., Goldstein, R. J., Ibele, W. E., Patankar, S. V., Simon, T. W., Kuehn, T. H., … Garrick, S. (2000). Heat transfer — a review of 1997 literature. International Journal of Heat and Mass Transfer, 43(14), 2431-2528. doi:10.1016/s0017-9310(99)00196-9Hoyas, S., Fajardo, P., Gil, A., & Perez-Quiles, M. J. (2014). Analysis of bifurcations in a Bénard–Marangoni problem: Gravitational effects. International Journal of Heat and Mass Transfer, 73, 33-41. doi:10.1016/j.ijheatmasstransfer.2014.01.061O’Shaughnessy, S. M., & Robinson, A. J. (2013). Heat transfer near an isolated hemispherical gas bubble: The combined influence of thermocapillarity and buoyancy. International Journal of Heat and Mass Transfer, 62, 422-434. doi:10.1016/j.ijheatmasstransfer.2013.02.064Celli, M., Barletta, A., & Alves, L. S. de B. (2015). Marangoni instability of a liquid film flow with viscous dissipation. Physical Review E, 91(2). doi:10.1103/physreve.91.023006Orszag, S. A. (1972). Comparison of Pseudospectral and Spectral Approximation. Studies in Applied Mathematics, 51(3), 253-259. doi:10.1002/sapm1972513253Canuto, C., Hussaini, M. Y., Quarteroni, A., & Zang, T. A. (1988). Spectral Methods in Fluid Dynamics. doi:10.1007/978-3-642-84108-8JIMÉNEZ, J., & HOYAS, S. (2008). Turbulent fluctuations above the buffer layer of wall-bounded flows. Journal of Fluid Mechanics, 611, 215-236. doi:10.1017/s0022112008002747Mancho, A. M., & Herrero, H. (2000). Instabilities in a laterally heated liquid layer. Physics of Fluids, 12(5), 1044-1051. doi:10.1063/1.870359Favre, E., Blumenfeld, L., & Daviaud, F. (1997). Instabilities of a liquid layer locally heated on its free surface. Physics of Fluids, 9(5), 1473-1475. doi:10.1063/1.869470Burguete, J., Mukolobwiez, N., Daviaud, F., Garnier, N., & Chiffaudel, A. (2001). Buoyant-thermocapillary instabilities in extended liquid layers subjected to a horizontal temperature gradient. Physics of Fluids, 13(10), 2773-2787. doi:10.1063/1.1398536Daviaud, F., & Vince, J. M. (1993). Traveling waves in a fluid layer subjected to a horizontal temperature gradient. Physical Review E, 48(6), 4432-4436. doi:10.1103/physreve.48.4432RILEY, R. J., & NEITZEL, G. P. (1998). Instability of thermocapillary–buoyancy convection in shallow layers. Part 1. Characterization of steady and oscillatory instabilities. Journal of Fluid Mechanics, 359, 143-164. doi:10.1017/s0022112097008343Mercier, J. F., & Normand, C. (1996). Buoyant‐thermocapillary instabilities of differentially heated liquid layers. Physics of Fluids, 8(6), 1433-1445. doi:10.1063/1.868920Yu, J.-J., Ruan, D.-F., Li, Y.-R., & Chen, J.-C. (2015). Experimental study on thermocapillary convection of binary mixture in a shallow annular pool with radial temperature gradient. Experimental Thermal and Fluid Science, 61, 79-86. doi:10.1016/j.expthermflusci.2014.10.01

Set-up analysis and Optimization of CFD Simulations for Radial Turbines

[EN] This paper proposes a CFD method for simulating radial turbocharger turbine flows. A review is presented of the computational model in terms of meshing, mesh movement strategy, and computational algorithm in turbomachinery CFD simulations. A novel local mesh independence analysis is developed for this purpose. This procedure is aimed at distributing the cells more efficiently by selecting suitable cell sizes for the different regions of the domain to optimize the use of the available computational resources. Pressure- and density-based solvers are compared. The influence of the moving-mesh strategy was analyzed, and small differences were observed in the region near the maximum efficiency point, while these differences increased when off-design conditions were considered. Finally, a comparison of the results with data from an experimental test bench shows that the proposed computational methodology can be used to characterize radial turbomachinery. The objective of the analysis and the optimization of the case configuration was to establish some general guidelines for CFD turbomachinery simulations.The authors are indebted to the Spanish Ministerio de Econom a y Competitividad through Project TRA 2010-16205.Galindo, J.; Hoyas, S.; Fajardo, P.; Navarro, R. (2013). Set-up analysis and Optimization of CFD Simulations for Radial Turbines. Engineering Applications of Computational Fluid Mechanics. 7(4):441-460. doi:10.1080/19942060.2013.11015484S44146074ANSYS (2009).Ansys Fluent 12.0 User’s Guide. Canonsburg, PA: ANSYS Inc.ANSYS (2011).ANSYS FLUENT Theory Guide. ANSYS Inc.Aymanns R, Scharf J, Uhlmann T, Lückmann D (2011). A revision of quasi steady modelling of turbocharger turbines in the simulation of pulse charged engines.16th Supercharging Conference.Hellström F (2010).Numerical Computations of the Unsteady Flow in Turbochargers. PhD thesis, Royal Institute of Technology KTH Fluid Physics.Hiereth H, Prenninger P (2007).Charging the Internal Combustion Engine. Springer Verlag.Japikse D, Baines NC (1997).Introduction to Turbomachinery. Oxford University Press.Liu Z, Hill DL (2000). Issues surrounding multiple frames of reference models for turbo compressor applications.Fifteenth International Compressor Engineering Conference, Purdue University, USA

A moving mesh generation strategy for solving an injector internal flow problem

[EN] The ability to handle complex geometries is an important part of transient calculations; therefore, the need for fully automatic mesh generation capable of dealing with such geometries is quite demanded. In this paper a specific approach to fully automatic three-dimensional mesh generation is presented. An approach to moving the generated mesh is also outlined. In particular, the simulation of a diesel injector needle movement is sought. The movement of the needle was calculated on the basis of injection rate experimental data and injection rate predicted data with steady state boundaries and geometry. The simulation was performed using the commercial code STAR-CD version 4.06. (C) 2010 Elsevier Ltd. All rights reserved.This research was funded by the Spanish Government in the framework of the Project "Caracterizacion experimental de la cavitacion en el flujo interno e influencia sobre modelos de chorro Diesel'', Reference TRA2007-68006-C02-01. SH and PF were partially supported by the Universidad Politecnica de Valencia under the program "Primeros Proyectos de investigacion'', in the framework of the project "Simulacion CFD de chorros Diesel en inyeccion directa: la atomizacion primaria'', Reference PAID-2759.Margot, X.; Hoyas, S.; Fajardo, P.; Patouna, S. (2010). A moving mesh generation strategy for solving an injector internal flow problem. Mathematical and Computer Modelling. 52:1143-1150. doi:10.1016/j.mcm.2010.03.018S114311505

Aggressive Surveillance Is Needed to Detect Endoleaks and Junctional Separation between Device Components after Zenith Fenestrated Aortic Reconstruction

Background Junctional separation and resulting type IIIa endoleak is a well-known problem after EVAR (endovascular aneurysm repair). This complication results in sac pressurization, enlargement, and eventual rupture. In this manuscript, we review the incidence of this late finding in our experience with the Cook Zenith fenestrated endoprosthesis (ZFEN, Bloomington, IN). Methods A retrospective review was performed of a prospectively maintained institutional ZFEN fenestrated EVAR database capturing all ZFENs implanted at a large-volume, academic hospital system. Patients who experienced junctional separation between the fenestrated main body and distal bifurcated graft (with or without type IIIa endoleak) at any time after initial endoprosthesis implantation were subject to further evaluation of imaging and medical records to abstract clinical courses. Results In 110 ZFENs implanted from October 2012 to December 2017 followed for a mean of 1.5 years, we observed a 4.5% and 2.7% incidence of clinically significant junctional separation and type IIIa endoleak, respectively. Junctional separation was directly related to concurrent type Ib endoleak in all 5 patients. Three patients presented with sac enlargement. One patient did not demonstrate any evidence of clinically significant endoleak and had a decreasing sac size during follow-up imaging. The mean time to diagnosis of modular separation in these patients was 40 months. Junctional separation was captured in surveillance in 2 patients and reintervened upon before manifestation of endoleak. However, the remaining 3 patients completed modular separation resulting in rupture and emergent intervention in 2 and an aortic-related mortality in the other. Conclusions Junctional separation between the fenestrated main and distal bifurcated body with the potential for type IIIa endoleak is an established complication associated with the ZFEN platform. Therefore, we advocate for maximizing aortic overlap during the index procedure followed by aggressive surveillance and treatment of stent overlap loss captured on imaging