Last 7 days
Bookmark and Share    
Full Text
Peer Reviewed
See detailTracing back the evolution of the candidate LBV HD 168625
Mahy, Laurent ULg; Hutsemekers, Damien ULg; Royer, P. et al

in Astronomy and Astrophysics (2016), 594

Context. The luminous blue variable phase is a crucial transitory phase that is not clearly understood in the massive star evolution. <BR /> Aims: We have obtained far-infrared Herschel/PACS imaging and ... [more ▼]

Context. The luminous blue variable phase is a crucial transitory phase that is not clearly understood in the massive star evolution. <BR /> Aims: We have obtained far-infrared Herschel/PACS imaging and spectroscopic observations of the nebula surrounding the candidate LBV HD 168625. By combining these data with optical spectra of the central star, we want to constrain the abundances in the nebula and in the star and compare them to trace back the evolution of this object. <BR /> Methods: We use the CMFGEN atmosphere code to determine the fundamental parameters and the CNO abundances of the central star whilst the abundances of the nebula are derived from the emission lines present in the Herschel/PACS spectrum. <BR /> Results: The far-infrared images show a nebula composed of an elliptical ring/torus of ejecta with a ESE-WNW axis and of a second perpendicular bipolar structure composed of empty caps/rings. We detect equatorial shells composed of dust and ionized material with different sizes when observed at different wavelengths, and bipolar caps more of less separated from the central star in Hα and mid-IR images. This complex global structure seems to show two different inclinations: ~40° for the equatorial torus and ~ 60° for the bipolar ejections. From the Herschel/PACS spectrum, we determine nebular abundances of N/H = 4.1 ± 0.8 × 10[SUP]-4[/SUP] and , as well as a mass of ionized gas of 0.17 ± 0.04 M[SUB]⊙[/SUB] and a neutral hydrogen mass of about 1.0 ± 0.3 M[SUB]⊙[/SUB] which dominates. Analysis of the central star reveals T[SUB]eff[/SUB] = 14 000 ± 2000 K, log g = 1.74 ± 0.05 and log (L/L[SUB]⊙[/SUB]) = 5.58 ± 0.11. We derive stellar CNO abundances of about N/H = 5.0 ± 1.5 × 10[SUP]-4[/SUP], C/H = 1.4 ± 0.5 × 10[SUP]-4[/SUP] and O/H = 3.5 ± 1.0 × 10[SUP]-4[/SUP], not significantly different from nebular abundances. All these measurements taken together are compatible with the evolutionary tracks of a star with an initial mass between 28 and 33 M[SUB]⊙[/SUB] and with a critical rotational rate between 0.3 and 0.4 that has lost its material during or just after the blue supergiant phase. Based in part on observations taken by Herschel satellite. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Based in part on observations collected at the European Southern Observatory, in Chile. [less ▲]

Detailed reference viewed: 19 (7 ULg)
Full Text
Peer Reviewed
See detailApsidal motion in the massive binary HD 152218
Rauw, Grégor ULg; Rosu, S.; Noels-Grötsch, Arlette ULg et al

in Astronomy and Astrophysics (2016), 594(A33), 1-12

Massive binary systems are important laboratories in which to probe the properties of massive stars and stellar physics in general. In this context, we analysed optical spectroscopy and photometry of the ... [more ▼]

Massive binary systems are important laboratories in which to probe the properties of massive stars and stellar physics in general. In this context, we analysed optical spectroscopy and photometry of the eccentric short-period early-type binary HD 152218 in the young open cluster NGC 6231. We reconstructed the spectra of the individual stars using a disentangling code. The individual spectra were then compared with synthetic spectra obtained with the CMFGEN model atmosphere code. We furthermore analysed the light curve of the binary and used it to constrain the orbital inclination and to derive absolute masses of (19.8 ± 1.5) and (15.0 ± 1.1) M⊙. Combining radial velocity measurements from over 60 yr, we show that the system displays apsidal motion at a rate of (2.04 ± .24)°/yr. Solving the Clairaut-Radau equation, we used stellar evolution models, obtained with the CLES code, to compute the internal structure constants and to evaluate the theoretically predicted rate of apsidal motion as a function of stellar age and primary mass. In this way, we determine an age of 5.8 ± 0.6 Myr for HD 152218, which is towards the higher end of, but compatible with, the range of ages of the massive star population of NGC 6231 as determined from isochrone fitting. [less ▲]

Detailed reference viewed: 18 (2 ULg)
See detailArchitectures du XX ème siècle à Liège
Frankignoulle, Pierre ULg

Diverse speeche and writing (2016)

Visite organisée le 1/10/2016 à l'intention de DOCOMOMO Allemagne

Detailed reference viewed: 17 (3 ULg)
Full Text
Peer Reviewed
See detailTowards a large scale aqueous sol-gel synthesis of doped TiO2: Study of various metallic dopings for the photocatalytic degradation of p-nitrophenol
Mahy, Julien ULg; Lambert, Stéphanie ULg; Léonard, Géraldine ULg et al

in Journal of Photochemistry and Photobiology A : Chemistry (2016), 329

In this paper, an easy aqueous sol-gel synthesis developed previously by Mahy et al. [J. Sol-Gel Sci. Technol. (2016)] is adapted to produce highly active TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2 ... [more ▼]

In this paper, an easy aqueous sol-gel synthesis developed previously by Mahy et al. [J. Sol-Gel Sci. Technol. (2016)] is adapted to produce highly active TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2+, Cr3+, Al3+, Mn2+, and Co2+ ions and Pt metallic nanoparticles. Samples are characterized by inductively coupled plasma–atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), Mössbauer spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption–desorption measurements and diffuse reflectance spectroscopy measurements. Results show that the samples are composed of anatase-brookite TiO2 nanoparticles with a spherical shape and mean diameter of around 5-8 nm and a surface area of between about 150 - 250 m2 g-1. In each doped sample, the dopant is present in the form added during the synthesis, given that the sample has not undergone any particular treatment. Photoactivity tests show improvement in catalyst activity for Fe3+, Ag+, Cu2+, Zn2+, and Al3+ ion and Pt metallic nanoparticle dopants, while a decrease of activity is obtained for Cr3+, Mn2+ and Co2+ ion dopants. For some dopants, the activity of TiO2 doped with metallic ions and synthesized from the aqueous sol-gel process is equal or superior to the activity of the commercial photocatalyst Degussa P25. Some mechanisms are proposed to explain these modifications of activity with doping. Furthermore, cost comparison at laboratory scale showed that Zn and Cu nitrate salt dopings are clearly less expensive for a halogen light (UV/visible) or low energy light enhanced catalyst and may be considered for industrial applications. Using this method, a large scale Zn-doped TiO2 photocatalyst is synthesized with properties homologous to the lab-scale product. Results show that the aqueous sol-gel synthesis developed previously can be easily adapted for doping in order to produce an up-scalable synthesis. [less ▲]

Detailed reference viewed: 79 (30 ULg)
Full Text
Peer Reviewed
See detailA large strain hyperelastic viscoelastic-viscoplastic-damage constitutive model based on a multi-mechanism non-local damage continuum for amorphous glassy polymers
Nguyen, Van Dung ULg; Lani, Frédéric; Pardoen, Thomas et al

in International Journal of Solids and Structures (2016), 96

A large strain hyperelastic phenomenological constitutive model is proposed to model the highly nonlinear, rate-dependent mechanical behavior of amorphous glassy polymers under isothermal conditions. A ... [more ▼]

A large strain hyperelastic phenomenological constitutive model is proposed to model the highly nonlinear, rate-dependent mechanical behavior of amorphous glassy polymers under isothermal conditions. A corotational formulation is used through the total Lagrange formalism. At small strains, the viscoelastic behavior is captured using the generalized Maxwell model. At large strains beyond a viscoelastic limit characterized by a pressure-sensitive yield function, which is extended from the Drucker-Prager one, a viscoplastic region follows. The viscoplastic flow is governed by a non-associated Perzyna-type flow rule incorporating this pressure-sensitive yield function and a quadratic flow potential in order to capture the volumetric deformation during the plastic process. The stress reduction phenomena arising from the post-peak plateau and during the failure stage are considered in the context of a continuum damage mechanics approach. The post-peak softening is modeled by an internal scalar, so-called softening variable, whose evolution is governed by a saturation law. When the softening variable is saturated, the rehardening stage is naturally obtained since the isotropic and kinematic hardening phenomena are still developing. Beyond the onset of failure characterized by a pressure-sensitive failure criterion, the damage process leading to the total failure is controlled by a second internal scalar, so-called failure variable. The final failure occurs when the failure variable reaches its critical value. To avoid the loss of solution uniqueness when dealing with the continuum damage mechanics formalism, a non-local implicit gradient formulation is used for both the softening and failure variables, leading to a multi-mechanism non-local damage continuum. The pressure sensitivity considered in both the yield and failure conditions allows for the distinction under compression and tension loading conditions. It is shown through experimental comparisons that the proposed constitutive model has the ability to capture the complex behavior of amorphous glassy polymers, including their failure. [less ▲]

Detailed reference viewed: 100 (52 ULg)
Full Text
Peer Reviewed
See detailAdvancing the integration of corporate sustainability measurement, management and reporting
Maas, Karen; Schaltegger, Stefan; Crutzen, Nathalie ULg

in Journal of Cleaner Production (2016), 133

Detailed reference viewed: 60 (5 ULg)
Full Text
Peer Reviewed
See detailX-ray and optical spectroscopy of the massive young open cluster IC 1805
Rauw, Grégor ULg; Nazé, Yaël ULg

in Astronomy and Astrophysics (2016), 594(A82), 19

Context. Very young open clusters are ideal places to study the X-ray properties of a homogeneous population of early-type stars. In this respect, the IC 1805 open cluster is very interesting as it hosts ... [more ▼]

Context. Very young open clusters are ideal places to study the X-ray properties of a homogeneous population of early-type stars. In this respect, the IC 1805 open cluster is very interesting as it hosts the O4 If+ star HD 15570 thought to be in an evolutionary stage intermediate between a normal O-star and a Wolf-Rayet star. Aims: Such a star could provide a test for theoretical models aiming at explaining the empirical scaling relation between the X-ray and bolometric luminosities of O-type stars. Methods: We have observed IC 1805 with XMM-Newton and further collected optical spectroscopy of some of the O-star members of the cluster. Results: The optical spectra allow us to revisit the orbital solutions of BD+60° 497 and HD 15558, and provide the first evidence of binarity for BD+60° 498. X-ray emission from colliding winds does not appear to play an important role among the O-stars of IC 1805. Notably, the X-ray fluxes do not vary significantly between archival X-ray observations and our XMM-Newton pointing. The very fast rotator BD+60° 513, and to a lesser extent the O4 If+ star HD 15570 appear somewhat underluminous. Whilst the underluminosity of HD 15570 is only marginally significant, its amplitude is found to be compatible with theoretical expectations based on its stellar and wind properties. A number of other X-ray sources are detected in the field, and the brightest objects, many of which are likely low-mass pre-main sequence stars, are analyzed in detail. [less ▲]

Detailed reference viewed: 14 (3 ULg)
Full Text
Peer Reviewed
See detailUsing PCB signatures and enantiomer fractions for source identification and to age date exposure
Megson, D; Focant, Jean-François ULg; Patterson, D et al

Conference (2016, October)

Detailed reference viewed: 19 (1 ULg)
Full Text
See detailDioxins! Hunting the Great White.
Focant, Jean-François ULg

Scientific conference (2016, October)

Detailed reference viewed: 21 (1 ULg)
Full Text
See detailA Simple Method for Thermal Characterization of Low-Melting Temperature Phase Change Materials (PCMs)
Salvador, Lucas ULg; Hastanin, Juriy ULg; Novello, Frédéric et al

in COMSOL 2016 Proceedings (2016, October)

The successful implementation of a high-efficient latent heat storage system necessitates an appropriate experimental approach to investigate and quantify the variations of the Phase Change Material (PCM ... [more ▼]

The successful implementation of a high-efficient latent heat storage system necessitates an appropriate experimental approach to investigate and quantify the variations of the Phase Change Material (PCM) thermal properties caused by its aging, as well as its potential demixing induced by cyclic freezing and melting. In this paper, we present a concept for the PCM characterization. The proposed method is relatively simple to be implemented. It consists of a cyclic cooling and melting of the PCM sample placed into a tube and monitoring its temperature evolution with a set of temperature sensors. In our work, the temperature evolution of the sample, as well as its sensitivity to the thermal parameters have been numerically investigated using the COMSOL Multiphysics® software. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Full Text
See detailMultimodal Connectivity-Based Parcellation of the Brain
Reuter, Niels; Plachti, Anna; Genon, Sarah ULg et al

Poster (2016, October)

Detailed reference viewed: 20 (2 ULg)
Full Text
See detailProjet BELCAM: télédétection des besoins et rendements des cultures
Wellens, Joost ULg

Speech/Talk (2016)

Detailed reference viewed: 17 (7 ULg)
Full Text
Peer Reviewed
See detailTransmission Efficiency of Cucumber Mosaic Virus by Myzus persicae According to Virus Strain and Aphid Clone from China
Bosquée, Emilie ULg; Yin, Ronling; Bragard, Claude et al

in Asian Journal of Plant Pathology (2016)

Background: Cucumber mosaic virus (CMV) is one of the most important viruses infecting vegetables in the fields throughout the world. Transmission efficiency of CMV could depend on the variability of ... [more ▼]

Background: Cucumber mosaic virus (CMV) is one of the most important viruses infecting vegetables in the fields throughout the world. Transmission efficiency of CMV could depend on the variability of virus strain but also aphid vector species and/or clones. Materials and Methods: By sequence analysis, the coat protein gene of CMV strains from different regions revealed that the CMV isolates used for this study belong to the same group. Both CMV strains and Myzus persicae (Sulzer) aphid clones were investigated for their role in viral dispersion by reciprocal tests on Nicotiana tabacum (L.) using the same clone of Myzus persicae towards different CMV strains or using one CMV strain on different Myzus persicae clones. Results: Virus transmission efficiency was found to be significantly influenced by selected CMV strains (from 5-30% of transmission rate for identical aphid clone) and also by the selected aphid clones (variation from 15-70% of transmission rate for identical virus strain). Conclusion: The CMV transmission efficiency depends on the variability of virus strain but also aphid vector clones. Combining the variability of CMV transmission rates for both aphid and virus sides, the prediction and modeling of virus spreading seems to be difficult to organize and are closely dependent on the variability of each protagonist-aphid and virus. [less ▲]

Detailed reference viewed: 33 (2 ULg)
Full Text
See detailLa philosophie de la conscience comme intertexte des Temps Modernes et de Critique
Franck, Thomas ULg

in Slamti, Sad; Chakir, Bouchra (Eds.) L'Interculturel dans la littérature et les arts. Matière et manière intertextuelles (2016)

Detailed reference viewed: 21 (5 ULg)
Full Text
Peer Reviewed
See detailOrganizaciones regionales y diversidad cultural: la diplomacia de la Unión Europea con el Mercosur entre la sombra de Hollywood y la acción intergubernamental
Vlassis, Antonios ULg

in Cuadernos de Información y Comunicación (2016), 21

Abstract. The aim of the article is double: on the one hand, to explore the EU’s ability to conduct a foreign audiovisual policy towards the Mercosur region and to promote the norms of the Convention on ... [more ▼]

Abstract. The aim of the article is double: on the one hand, to explore the EU’s ability to conduct a foreign audiovisual policy towards the Mercosur region and to promote the norms of the Convention on diversity of cultural expressions; on the other hand, to analyze the impact of the EU audiovisual policy model on the development of the Mercosur audiovisual cooperation and to focus on the main forces shaping the Mercosur audiovisual landscape. The article seeks to emphasize why and how the EU pursues an audiovisual foreign policy towards the Mercosur region, for which purposes as well as to highlight the resistances. In this sense, it is more concerned with understanding how the EU’s audiovisual diplomacy interplays with other main factors, such as the governmental action, namely the EU and Mercosur members’ audiovisual diplomacy and the practices of private sector (Hollywood and big media conglomerates). [less ▲]

Detailed reference viewed: 19 (4 ULg)
Full Text
Peer Reviewed
See detailA review of Silurian dispersed spore assemblages from the Arabian Plate: biostratigraphy and palaeogeography
Wellman, CH; Steemans, Philippe ULg; Breuer, P et al

Conference (2016, October)

Detailed reference viewed: 29 (3 ULg)
Full Text
See detailLe bouleau, une essence qui s'impose. Description de la ressource dans son aire de distribution
Dubois, Héloïse ULg; Latte, Nicolas ULg; Lecomte, Hugues et al

in FORÊT.NATURE (2016), 140

L'essentiel de la ressource en bouleau (verruqueux et pubescent) se situe en Russie et en Scandinavie (15 milliards de m³) et cette ressource augmente graduellement depuis plusieurs années. Il y est ... [more ▼]

L'essentiel de la ressource en bouleau (verruqueux et pubescent) se situe en Russie et en Scandinavie (15 milliards de m³) et cette ressource augmente graduellement depuis plusieurs années. Il y est fortement valorisé en sciage, déroulage et trituration. En Europe de l'Ouest, cette croissance s'observe aussi, même si seulement 1 % de la ressource s'y concentre (dû notamment à la plus grande diversité d'essences commerciales présentes). En Wallonie, les évolutions du contexte socio-économique et environnemental jouent en faveur d'une augmentation de la présence du bouleau (parcelles non reboisées, entretien insuffisant, mélanges spontanés...). Le bouleau représente souvent une belle opportunité pour les mélanges, une excellente essence d'accompagnement et une diversification de la production. Mais, sans une sylviculture adaptée, les grumes sont généralement de faible dimension et présentent de nombreux défauts. C'est le cas de l'essentiel de la ressource actuelle en Wallonie. Aujourd'hui, les besoins sont de mieux le connaître, notamment les opportunités de valorisation, et d'aboutir à des recommandations sylvicoles. Il ne s'agit donc pas de vouloir faire du bouleau à tout prix mais plutôt de tirer profit d'une étape transitoire de la succession forestière. [less ▲]

Detailed reference viewed: 16 (3 ULg)
Full Text
Peer Reviewed
See detailConjoint influence of mind-wandering and sleepiness on task performance
Stawarczyk, David ULg; D'Argembeau, Arnaud ULg

in Journal of Experimental Psychology. Human Perception & Performance (2016), 42(10), 1587-15600

Recent research suggests that sleepiness and mind-wandering—the experience of thoughts that are both stimulus-independent and task-unrelated—frequently co-occur and are both associated with poorer ... [more ▼]

Recent research suggests that sleepiness and mind-wandering—the experience of thoughts that are both stimulus-independent and task-unrelated—frequently co-occur and are both associated with poorer cognitive functioning. Whether these two phenomena have distinguishable effects on task performance remains unknown, however. To investigate this question, we employed the online experience sampling of mind-wandering episodes and subjective sleepiness during a laboratory task (the Sustained Attention to Response Task; SART), and also assessed mind-wandering frequency and sleep-related disturbances in daily life using self-report questionnaires. The results revealed that the tendency to experience mind-wandering episodes during the SART and daily life was associated with higher levels of daytime sleepiness and sleep-related disturbances. Importantly, however, mind-wandering and sleepiness were independent predictors of SART performance at both the within- and between-individuals levels. These findings demonstrate that, although mind-wandering and sleepiness frequently co-occur, these two phenomena have distinguishable and additive effects on task performance. [less ▲]

Detailed reference viewed: 199 (8 ULg)
Full Text
See detailPotential for Composite Analysis in the Black Sea
Capet, Arthur ULg; Mason, Evan; Troupin, Charles et al

Conference (2016, October)

Detailed reference viewed: 10 (1 ULg)