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See detailFirst synthesis of a '1,2-diquinone-calix[4]arene'. Interaction of its reduced form with Ag+
Vataj, Rame; Ridaoui, Hassan; Louati, Alain et al

in Journal of Electroanalytical Chemistry (2002), 519(1-2), 123129

Electrochemical oxidation of 5,11,17,23-tetra-tert-butyl-25,26-bis(diphenylphosphinoylmethoxy)-27,28-dihydroxycalix[4]arene (3), a calixarene with two phosphoryl units appended on proximal positions ... [more ▼]

Electrochemical oxidation of 5,11,17,23-tetra-tert-butyl-25,26-bis(diphenylphosphinoylmethoxy)-27,28-dihydroxycalix[4]arene (3), a calixarene with two phosphoryl units appended on proximal positions, affords the corresponding '1,2-diquinonecalix[4]arene' (4). The formation of 4 results from nucleophilic attack of residual water on anodically generated diphenoxylium. cations. Preliminary voltammetric experiments in CH3CN on a platinum electrode showed that 4 is suitable for electrochemical detection of the silver metal cation. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 116 (6 ULg)
See detailThe first three billion years of life Evolution
Javaux, Emmanuelle ULg

Conference (2013, June)

Detailed reference viewed: 44 (4 ULg)
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See detailFirst trends towards a field odour detector for environmental applications
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Wiertz, V. et al

in Weimar, Udo (Ed.) Proceedings of ISOEN 99 (1999)

Detailed reference viewed: 23 (2 ULg)
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See detailFirst unambiguous asteroseismologic modelling of a gamma Doradus star
Moya, A.; Grigahcene, A.; Suárez, J. C. et al

in Memorie della Società Astronomica Italiana : Journal of the Italian Astronomical Society (2006), 77

An asteroseismologic model of the gamma Dor star 9 Aurigae is discussed in this work. This is the first time a complete asteroseismologic scheme for analyzing gamma Dor stars is applied. From standard ... [more ▼]

An asteroseismologic model of the gamma Dor star 9 Aurigae is discussed in this work. This is the first time a complete asteroseismologic scheme for analyzing gamma Dor stars is applied. From standard photometric observations (at least three oscillation frequencies, a photometric error box in the HR diagram and multicolor photometric observations, in this case in the Strömgren system) we can reduce the possible theoretical models for this star, providing constraints to the stellar parameters as mass, overshooting, metallicity, MLT parameter alpha , Brunt-Väiälä integral (I[SUB]th[/SUB]), etc. Simultaneously, an estimate of the modal identification of the observed frequencies is also obtained. This can be possible by the application, for the first time, of a complete procedure where different theoretical and computational techniques, recently developed, are linked and compared with photometric observations. The Frequency Ratio Method (FRM) and the Time Dependent Convection (TDC) theory are the basis of this complete procedure. [less ▲]

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See detailThe first Upper Paleolithic human remains from Belgium: Aurignacian, Gravettian and Magdalenian fossils at the “troisième caverne” of Goyet
Rougier, H.; Crevecoeur, I.; Beauval, C. et al

Poster (2013)

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See detailFirst vortex entry into a perpendicularly magnetized superconducting thin film
Gutierrrez, Joffre; Raes, Bart; Van de Vondel, Joris et al

in Physical Review. B : Condensed Matter (2013), 88

In type-II superconductors, the flux-free state (Meissner state) may be invaded by vortices bearing quantized flux once H is above the lower critical field Hc1. However, the actual first flux penetration ... [more ▼]

In type-II superconductors, the flux-free state (Meissner state) may be invaded by vortices bearing quantized flux once H is above the lower critical field Hc1. However, the actual first flux penetration does not occur at Hc1 due to the presence of a surface barrier and the fact that the Meissner state may also exist as a metastable state up to a larger (superheating) field. In this work we determine the field for the first vortex penetration in superconductors, by directly imaging the first vortex threading a superconducting Pb film with antidots. We find that the first vortex penetration occurs when the surface superconducting currents reach the depairing current, locally breaking superconductivity and allowing a vortex to nucleate. [less ▲]

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See detailThe First World War in French Children's Literature of Today: Between Pacifism and Unilateral View
Delbrassine, Daniel ULg

in Hans-Heino Ewers (Ed.) Erster Weltkrieg: Kindheit, Jugend und Literatur (2016)

Analyse d'un corpus de 22 récits (albums et romans en français, 1998-2013). Mise en évidence de certains choix narratifs et idéologiques: unilatéralisme français de la vision, pacifisme militant, silence ... [more ▼]

Analyse d'un corpus de 22 récits (albums et romans en français, 1998-2013). Mise en évidence de certains choix narratifs et idéologiques: unilatéralisme français de la vision, pacifisme militant, silence sur les causes du conflit... [less ▲]

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See detailThe first X-ray survey of Galactic Luminous Blue Variables
Nazé, Yaël ULg; Rauw, Grégor ULg; Hutsemekers, Damien ULg

in Astronomy and Astrophysics (2012), 538

Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional ... [more ▼]

Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional Luminous Blue Variable (LBV) phase remain unknown. Methods: Using a dedicated but limited XMM survey as well as archival XMM and Chandra observations, we performed the first X-ray survey of LBVs: about half of the known LBVs or candidate LBVs are studied. Results: Apart from the well known X-ray sources eta Car and Cyg OB2 #12, four additional LBVs are detected in this survey, though some doubt remains on the association with the X-ray source for two of these. For the other LBVs, upper limits on the flux were derived, down to $\log[L_{\rm X}/L_{\rm BOL}]-9.4$ for PCyg. This variety in the strength of the X-ray emission is discussed, with particular emphasis on the potential influence of binarity. [less ▲]

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See detailFirst year prognosis after myocardial infarction assassed from simple clinical findings
Smeets, J. P.; Foidart, G.; Dubois, Christophe ULg et al

Poster (1982, September)

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See detailFirst ‘in situ’ determination of gas transport coefficients (DO2, DAr and DN2 ) from bulk gas 2 concentration measurements (O2, N2, Ar) in natural sea ice
Crabeck, O.; Delille, Bruno ULg; Rysgaard, S. et al

in Journal of Geophysical Research. Oceans (2014), 119

We report bulk gas concentrations of O2, N2 and Ar, as well as their transport coefficients, in natural landfast subarctic sea ice in southwest Greenland. The observed bulk ice gas composition was 27.5 ... [more ▼]

We report bulk gas concentrations of O2, N2 and Ar, as well as their transport coefficients, in natural landfast subarctic sea ice in southwest Greenland. The observed bulk ice gas composition was 27.5% O2, 71.4% N2 and 1.09% Ar. Most previous studies suggest that convective transport is the main driver of gas displacement in sea ice and have neglected diffusion processes. According to our data, brines were stratified within the ice, so that no convective transport could occur within the brine system. Therefore, diffusive transport was the main driver of gas migration. By analysing the temporal evolution of an internal gas peak within the ice, we deduced the bulk gas transport coefficients for oxygen (DO2), argon (DAr) and nitrogen (DN222 ). The values fit to the few existing estimates from experimental work, and are close to the diffusivity values in water (10-5 cm2 s-124 ). We suggest that gas bubbles escaping from the brine to the atmosphere - as the ice gets more permeable during melt could be responsible for the previously reported high transport coefficients. These results underline that when there is no convective transport within the sea ice, the transport of gas by diffusion through the brines, either in the liquid or gaseous phases, is a major factor in controlling the ocean–atmosphere exchange. [less ▲]

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See detailFIRST, a fibered aperture masking instrument. I. First on-sky test results
Huby, Elsa ULg; Perrin, G.; Marchis, F. et al

in Astronomy and Astrophysics (2012), 541

Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single ... [more ▼]

Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single-mode fibers, a novel technique that is aimed at high dynamic range imaging with high angular resolution. Methods: The prototype has been tested with the Shane 3-m telescope at Lick Observatory. The entrance pupil is divided into sub-pupils feeding single-mode fibers. The flux injection into the fibers is optimized by a segmented mirror. The beams are spectrally dispersed and recombined in a non-redundant exit configuration in order to retrieve all contrasts and phases independently. Results: The instrument works at visible wavelengths between 600 nm and 760 nm and currently uses nine of the 30 43 cm sub-apertures constituting the full pupil. First fringes were obtained on Vega and Deneb. Stable closure phases were measured with standard deviations on the order of 1 degree. Closure phase precision can be further improved by addressing some of the remaining sources of systematic errors. While the number of fibers used in the experiment was too small to reliably estimate visibility amplitudes, we have measured closure amplitudes with a precision of 10% in the best case. Conclusions: These first promising results obtained under real observing conditions validate the concept of the fibered aperture masking instrument and open the way for a new type of ground-based instrument working in the visible. The next steps of the development will be to improve the stability and the sensitivity of the instrument in order to achieve more accurate closure phase and visibility measurements, and to increase the number of sub-pupils to reach full pupil coverage. [less ▲]

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See detailFIRST, a fibered aperture masking instrument. II. Spectroscopy of the Capella binary system at the diffraction limit
Huby, Elsa ULg; Duchêne, G.; Marchis, F. et al

in Astronomy and Astrophysics (2013), 560

Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to ... [more ▼]

Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to demonstrate the high angular resolution capability of the instrument and to show that the spectral resolution of the instrument enables characterization of stellar companions. Methods: The FIRST-18 instrument is an improved version of FIRST-9 that simultaneously recombines two sets of nine fibers instead of one, thus greatly enhancing the (u, v) plane coverage. We report on observations of the binary system Capella at three epochs over a period of 14 months (≳4 orbital periods) with FIRST-18 mounted on the 3 m Shane telescope at Lick Observatory. The binary separation during our observations ranges from 0.8 to 1.2 times the diffraction limit of the telescope at the central wavelength of the spectral band. Results: We successfully resolved the Capella binary system at all epochs, with an astrometric precision as good as 1 mas under the best observing conditions. FIRST also gives access to the spectral flux ratio between the two components directly measured with an unprecedented spectral resolution of R ~ 300 over the 600-850 nm range. In particular, our data allow detection of the well-known overall slope of the flux ratio spectrum, leading to an estimation of the "pivot" wavelength of 0.64 ± 0.01 μm, at which the cooler component becomes the brightest. Spectral features arising from the difference in effective temperature of the two components (specifically the Hα line, TiO, and CN bands) have been used to constrain the stellar parameters. The effective temperatures we derive for both components are slightly lower (5-7%) than the well-established properties for this system. This difference mainly comes from deeper molecular features than those predicted by state-of-the-art stellar atmospheric models, suggesting that molecular line lists used in the photospheric models are incomplete and/or oscillator strengths are underestimated, most likely concerning the CN molecule. Conclusions: These results demonstrate the power of FIRST, which is a fibered pupil remapping-based instrument, in terms of high angular resolution and show that the direct measurement of the spectral flux ratio provides valuable information to characterize little known companions. [less ▲]

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See detailFIRST, a fibered aperture masking instrument: on-sky results
Huby, Elsa ULg; Perrin, Guy; Marchis, Franck et al

in Ground-based and Airborne Instrumentation for Astronomy IV (2012, September 01)

We present on-sky results obtained with the visible light prototype of the Fibered Imager foR Single Telescope (FIRST) mounted on the 3-m Shane Telescope at Lick Observatory and using its Adaptive Optics ... [more ▼]

We present on-sky results obtained with the visible light prototype of the Fibered Imager foR Single Telescope (FIRST) mounted on the 3-m Shane Telescope at Lick Observatory and using its Adaptive Optics system. This instrument is dedicated to high angular resolution and high dynamic range imaging. Its principle combines both techniques of single-mode fiber interferometry and pupil remapping. Simulations predict a dynamic range up to 10[SUP]6[/SUP] at /D, or at a few tens of milliarcseconds at 630nm using an 8-m telescope. Laboratory experiments based on a 9-fiber prototype working in the 600nm-900nm spectral band successfully demonstrated the power of the concept. The same prototype has been set-up on the 3-m Shane telescope in July 2010. In this paper, we present the on-sky results obtained in October 2011 with an improved version of the instrument using 18 fibers. They clearly show the detection of the binary star Capella at the diffraction limit of the telescope.λ [less ▲]

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See detailFIRST, a fibered aperture masking instrument: Results of the Lick observing campaign
Bordwell, Baylee; Duchene, Gaspard; Huby, Elsa ULg et al

Poster (2015, January 01)

FIRST is a prototype instrument aimed at achieving high dynamic range and angular resolution in ground-based images at visible wavelengths near the diffraction limit. FIRST utilizes an aperture masking ... [more ▼]

FIRST is a prototype instrument aimed at achieving high dynamic range and angular resolution in ground-based images at visible wavelengths near the diffraction limit. FIRST utilizes an aperture masking-like technique that makes use of single-mode fibers and pupil remapping to maximize the area of the telescope mirror in use. While located at Lick observatory in 2011 and 2012, FIRST observed 25 binary systems with the Shane 3m telescope, with separations ranging from 20 to 200 mas, comparable to the 50 mas diffraction limit for our central wavelength. Huby et al. (2013) has reported results for the Capella system that established the utility of FIRST for characterizing stellar binaries using the directly measured spectral flux ratio. Using an improved data analysis pipeline, we obtained closure phase measurements for a majority of the targets observed at Lick, and derived angular separations and spectral flux ratios. From the spectral flux ratios we obtained spectra for the companions over at least 600-850 nm with R~300. Finally, by obtaining results for many binary systems we have better constrained the current performance of FIRST, which has an exciting future ahead at its current location behind SCExAO at the Subaru 8.2 m telescope, where it will eventually become available for general use by the astronomical community. [less ▲]

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See detailFIRST, a high dynamic range imager, mounted on the 3-m Shane Telescope
Huby, Elsa ULg

Scientific conference (2012, April)

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See detailFIRST, Fibered Imager foR a Single Telescope
Huby, Elsa ULg

Conference (2013, February)

Detailed reference viewed: 8 (0 ULg)