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See detailMultiwalled carbon nanotube/poly(epsilon-caprolactone) nanocomposites with exceptional electromagnetic interference shielding properties
Thomassin, Jean-Michel ULg; Lou, Xudong; Pagnoulle, Christophe et al

in Journal of Physical Chemistry C (2007), 111(30), 11186-11192

Multiwalled carbon nanotubes (MWNTs) with two different diameters were dispersed within poly(ε-caprolactone) (PCL) by melt-blending and coprecipitation, respectively, with the purpose to impart good ... [more ▼]

Multiwalled carbon nanotubes (MWNTs) with two different diameters were dispersed within poly(ε-caprolactone) (PCL) by melt-blending and coprecipitation, respectively, with the purpose to impart good electromagnetic interference shielding properties to the polyester. Transmission electron microscopy showed that the MWNTs were uniformly dispersed as single nanotubes within the matrix. Because the nanotubes were broken down during melt-blending, the percolation threshold was observed at a lower filler content in the case of coprecipitation. Substitution of poly(ethylene-co-octene), poly(vinyl chloride), polypropylene, and polystyrene for PCL resulted in a much lower shielding efficiency. Finally, polycarbonate and poly(methyl methacrylate) appeared as promising substitutes for PCL, suggesting that π−π interactions between the nanotubes and constitutive carbonyl units of the polymers would be beneficial to the dispersion and ultimately to the electrical properties of the nanocomposites. [less ▲]

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See detailA multiwavelength investigation of the massive eclipsing binary Cyg OB2 #5
Linder, Natacha ULg; Rauw, Grégor ULg; Manfroid, Jean ULg et al

in Astronomy and Astrophysics (2009), 495

Context. The properties of the early-type binary Cyg OB2 #5 have been debated for many years and spectroscopic and photometric investigations yielded conflicting results. Aims. We have attempted to ... [more ▼]

Context. The properties of the early-type binary Cyg OB2 #5 have been debated for many years and spectroscopic and photometric investigations yielded conflicting results. Aims. We have attempted to constrain the physical properties of the binary by collecting new optical and X-ray observations. Methods. The optical light curves obtained with narrow-band continuum and line-bearing filters are analysed and compared. Optical spectra are used to map the location of the He II $\lambda $ 4686 and H$\alpha $ line-emission regions in velocity space. New XMM-Newton as well as archive X-ray spectra are analysed to search for variability and constrain the properties of the hot plasma in this system. Results. We find that the orbital period of the system slowly changes though we are unable to discriminate between several possible explanations of this trend. The best fit solution of the continuum light curve reveals a contact configuration with the secondary star being significantly brighter and hotter on its leading side facing the primary. The mean temperature of the secondary star turns out to be only slightly lower than that of the primary, whilst the bolometric luminosity ratio is found to be 3.1. The solution of the light curve yields a distance of $925 \pm 25$ pc much lower than the usually assumed distance of the Cyg OB2 association. Whilst we confirm the existence of episodes of higher X-ray fluxes, the data reveal no phase-locked modulation with the 6.6 day period of the eclipsing binary nor any clear relation between the X-ray flux and the 6.7 yr radio cycle. Conclusions. The bright region of the secondary star is probably heated by energy transfer in a common envelope in this contact binary system as well as by the collision with the primary's wind. The existence of a common photosphere probably also explains the odd mass-luminosity relation of the stars in this system. Most of the X-ray, non-thermal radio, and possibly $\gamma$-ray emission of Cyg OB2 #5 is likely to arise from the interaction of the combined wind of the eclipsing binary with at least one additional star of this multiple system. [less ▲]

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See detailMultiwavelength Observations of Gamma-ray Binary Candidates
McSwain, M.V.; Chernyakova, M.; Malishev, D. et al

in 2012 Fermi Symposium proceedings - eConf C121028 (2012, October)

There are currently only six known high mass X-­‐ray binaries (HMXBs) that also exhibit MeV, GeV, and/or TeV emission ("gamma-­‐ray binaries"). Expanding the sample of gamma-­‐ray binaries and identifying ... [more ▼]

There are currently only six known high mass X-­‐ray binaries (HMXBs) that also exhibit MeV, GeV, and/or TeV emission ("gamma-­‐ray binaries"). Expanding the sample of gamma-­‐ray binaries and identifying unknown Fermi sources are currently of great interest to the community. Based upon their positional coincidence with the unidentified Fermi sources 1FGL J1127.7-­‐6244c and 1FGL J1808.5-­‐1954c, the Be stars HD 99771 and HD 165783 have been proposed as gamma-­‐ray binary candidates. During Fermi Cycle 4, we have performed multiwavelength observations of these sources using XMM-­‐Newton and the CTIO 1.5m telescope. We do not confirm high energy emission from the Be stars. Here we examine other X-­‐ray sources in the X-­‐ray sources in the field of view that are potential counterparts to the Fermi sources. [less ▲]

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See detailMULTIWAVELENGTH OBSERVATIONS OF THE RUNAWAY BINARY HD 15137
McSwain, M. V.; De Becker, Michaël ULg; Roberts, M. S. E. et al

in Astronomical Journal (The) (2010), 139

HD 15137 is an intriguing runaway O-type binary system that offers a rare opportunity to explore the mechanism by which it was ejected from the open cluster of its birth. Here, we present recent blue ... [more ▼]

HD 15137 is an intriguing runaway O-type binary system that offers a rare opportunity to explore the mechanism by which it was ejected from the open cluster of its birth. Here, we present recent blue optical spectra of HD 15137 and derive a new orbital solution for the spectroscopic binary and physical parameters of the O star primary. We also present the first XMM-Newton observations of the system. Fits of the EPIC spectra indicate soft, thermal X-ray emission consistent with an isolated O star. Upper limits on the undetected hard X-ray emission place limits on the emission from a proposed compact companion in the system, and we rule out a quiescent neutron star (NS) in the propeller regime or a weakly accreting NS. An unevolved secondary companion is also not detected in our optical spectra of the binary, and it is difficult to conclude that a gravitational interaction could have ejected this runaway binary with a low mass optical star. HD 15137 may contain an elusive NS in the ejector regime or a quiescent black hole with conditions unfavorable for accretion at the time of our observations. [less ▲]

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See detailThe multiwavelength picture of star formation in the very young open cluster NGC6383
Rauw, Grégor ULg; De Becker, Michaël ULg

in Reipurth, Bo (Ed.) Handbook of Star Forming Region. Volume 2: The Southern Sky (2008)

We review the properties of the very young (˜ 2 Myr) open cluster NGC 6383. The cluster is dominated by the massive binary HD 159176 (O7 V + O7 V). The distance to NGC 6383 is consistently found to be 1.3 ... [more ▼]

We review the properties of the very young (˜ 2 Myr) open cluster NGC 6383. The cluster is dominated by the massive binary HD 159176 (O7 V + O7 V). The distance to NGC 6383 is consistently found to be 1.3 ± 0.1 kpc and the average reddening is determined to be E(bv) = 0.32 ± 0.02. Several pre-main sequence candidates have been identified using different criteria relying on the detection of emission lines, infrared excesses, photometric variability and X-ray emission. [less ▲]

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See detailA Multiwavelength Study of the Runaway Binaries HD 14633 and HD 15137
McSwain, M Virginia; De Becker, Michaël ULg; Roberts, Mallory S E et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

The runaway O-type binaries HD 14633 and HD 15137 were likely ejected from the cluster of their birth by supernovae explosions in close binaries. Here we present recent optical spectra to update the ... [more ▼]

The runaway O-type binaries HD 14633 and HD 15137 were likely ejected from the cluster of their birth by supernovae explosions in close binaries. Here we present recent optical spectra to update the orbital solutions of the binaries and study the physical parameters of the O star primaries. We also present XMM-Newton observations of both systems that attempt to detect hard power-law emission from compact companions. EPIC spectra of HD 14633 at periastron and apastron reveal a non-thermal X-ray flux component that is variable during the orbit. Our EPIC spectra of HD 15137 indicate thermal X-ray emission consistent with an isolated O star. We provide an upper limit on the emission from a compact companion in HD 15137. [less ▲]

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See detailThe multiwavelength view of hot, massive stars
Rauw, Grégor ULg; De Becker, Michaël ULg; Nazé, Yaël ULg et al

in Bulletin de la Société Royale des Sciences de Liège (2011), 80

Massive stars are certainly among the most fascinating objects of stellar populations. They trigger many astrophysical processes from star formation to the chemical enrichment of the interstellar medium ... [more ▼]

Massive stars are certainly among the most fascinating objects of stellar populations. They trigger many astrophysical processes from star formation to the chemical enrichment of the interstellar medium. Yet, their properties are still not fully understood and these objects are therefore at the core of many ongoing research activities. With the advent of new, high-performance, ground-based and space-borne facilities, the multi-wavelength investigation of hot, massive stars has definitely been boosted over the last decade. It is indeed nowadays possible to study these objects over a wide part of the electromagnetic spectrum, all the way from radio waves to gamma-rays. Motivated by this fact, we decided to organize a conference devoted to this topic in the framework of the well-established series of Liege International Astrophysical Colloquia (LIAC). The resonance in the community was extremely positive, with many proposals for high-quality contributions. During the week of 12 - 16 July 2010, 138 astrophysicists, from institutes in 21 countries all over the world, gathered in Liege to discuss how the multi-wavelength approach has revolutionized their research on massive stars. The colloquium was organized into five thematic sessions, and the present proceedings are organized along the same chapters: (1) stellar winds, diagnostics across the electromagnetic spectrum; (2) massive star formation, confronting theory and observation; (3) evolution and interaction of massive stars with their environment; (4) future instrumentation and its application to massive star research; (5) massive binaries: interaction and evolution. [less ▲]

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See detailMultiyear homing and fidelity to residence areas by individual barbel (Barbus barbus)
Ovidio, Michaël ULg; Parkinson, Denis; Philippart, Jean-Claude ULg et al

in Belgian Journal of Zoology (2007), 137(2), 183-190

Nine barbels (Barbus barbus) from the River Ourthe (River Meuse basin) were equipped with transmitters programmed to switch ON during two consecutive spawning seasons in 1998 and 1999 (April to July). Six ... [more ▼]

Nine barbels (Barbus barbus) from the River Ourthe (River Meuse basin) were equipped with transmitters programmed to switch ON during two consecutive spawning seasons in 1998 and 1999 (April to July). Six of the nine barbels tracked in 1998 were also tracked in 1999 during the same period. The length of the spawning migration ranged from 200 to 22700m. After the spawning activity observed from 12-16 May 1998 and 4-6 May 1999, the barbels homed to the site occupied before spawning. Each barbel used the same spawning area in 1998 and 1999, despite the presence of other spawning sites on their migratory route. These observations revealed the existence of strict reproductive homing in the barbel and a long-term fidelity to particular resting places. [less ▲]

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See detailMultiyear infrared solar spectroscopic measurements of HCN, CO, C2H6,and C2H2 tropospheric columns above Lauder, New Zealand (45 degrees S latitude)
Rinsland, Curtis P.; Jones, Nicholas B.; Connor, Brian J. et al

in Journal of Geophysical Research. Atmospheres (2002), 107(D14),

[1] Near-simultaneous, 0.0035 or 0.007 cm(-1) resolution infrared solar absorption spectra of tropospheric HCN, C2H2, CO, and C2H6 have been recorded from the Network for the Detection of Stratospheric ... [more ▼]

[1] Near-simultaneous, 0.0035 or 0.007 cm(-1) resolution infrared solar absorption spectra of tropospheric HCN, C2H2, CO, and C2H6 have been recorded from the Network for the Detection of Stratospheric Change station in Lauder, New Zealand (45.04degreesS, 169.68degreesE, 0.37 km altitude). All four molecules were measured on over 350 days with HCN and C2H2 reported for the first time based on a new analysis procedure that significantly increases the effective signal-to-noise of weak tropospheric absorption features in the measured spectra. The CO measurements extend by 2.5 years a database of measurements begun in January 1994 for CO with improved sensitivity in the lower and middle troposphere. The C2H6 measurements lengthen a time series begun in July 1993 with peak sensitivity in the upper troposphere. Retrievals of all four molecules were obtained with an algorithm based on the semiempirical application of the Rodgers optimal estimation technique. Columns are reported for the 0.37- to 12-km-altitude region, approximately the troposphere above the station. The seasonal cycles of all four molecules are asymmetric, with minima in March-June and sharp peaks and increased variability during August-November, which corresponds to the period of maximum biomass burning near the end of the Southern Hemisphere tropical dry season. Except for a possible HCN column decrease, no evidence was found for a statistically significant long-term trend. [less ▲]

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See detailMulti‐scale modelling of fibre reinforced composite with non‐local damage variable
Wu, Ling ULg; Noels, Ludovic ULg; Adam, Laurent et al

Conference (2011, July)

Classical finite element simulations face the problems of losing uniqueness and strain localization when the strain softening of materials is involved. Thus, when using continuum damage model or ... [more ▼]

Classical finite element simulations face the problems of losing uniqueness and strain localization when the strain softening of materials is involved. Thus, when using continuum damage model or plasticity softening model, numerical convergence will not be obtained with the refinement of the finite element discretization when strain localization occurs. Gradient-enhanced softening and non-local continua models have been proposed by several researchers in order to solve this problem. In such approaches, the spatial gradients of state variables are incorporated in the macroscopic constitutive equation [1, 2]. However, when dealing with complex heterogeneous materials, a direct simulation of the macroscopic structures is unreachable, motivating the development of non-local homogenization schemes [3]. In our work, a gradient-enhanced homogenization procedure is proposed for fiber reinforced materials. In the approach, the fiber is assumed to remain linear elastic while the matrix material is modeled as elasto-plastic [4] coupled with damage and is described by a non-local constitutive model [5]. Toward this end, the mean-field homogenization is based on the knowledge of the macroscopic deformation tensors, internal variables and their gradients, which are applied to a micro-structural representative volume element (RVE). Macro-stress is then obtained from a homogenization process. This procedure is applied to simulate damage process occurring in unidirectional carbon-fiber reinforced epoxy composites submitted to different loading histories. [less ▲]

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See detailMulti‐spectral simultaneous observations of Saturn's aurorae in Jan. 2009
Lamy, L.; Prange, R.; Gustin, Jacques ULg et al

Conference (2012)

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See detailMulty-year cycles observed in air temperature data and proxy series
Mabille, Georges ULg; Nicolay, Samuel ULg

in European Physical Journal. Special Topics (2009), 174

First, palaeoclimatic time series are analyzed under the lens of the continuous wavelet transform. Two cycles, of period 30 and 43 months respectively, are detected in millennial temperature ... [more ▼]

First, palaeoclimatic time series are analyzed under the lens of the continuous wavelet transform. Two cycles, of period 30 and 43 months respectively, are detected in millennial temperature reconstructions. These rhythms correspond to the ones detected in weather station temperature records in a previous study of the authors. It is then showed that most parts of the globe are affected by at least one of the two cycles. Their relationship with the main climatic indices is also investigated, as well as the statistical significance of the observations. [less ▲]

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See detailEl mundo sobre el papel. El impacto de la escritura y la lectura en la estructura del conocimiento
Olson, David R.; Willson, Patricia ULg

Book published by Editorial Gedisa (1999)

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See detailMUNE in the last 30 years: what can we expect of it in practice?
WANG, François-Charles ULg; GERARD, Pascale ULg; BOUQUIAUX, Olivier ULg

in Correspondances en Nerf & Muscle (2004)

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See detailMunkoyo : des racines comme sources potentielles en enzymes amylolytiques et une boisson fermentée traditionnelle (synthèse bibliographique)
Foma, Roland Kibwega; Destain, Jacqueline ULg; Kayisu, Kalenga et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(2), 352-363

Detailed reference viewed: 21 (6 ULg)