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See detailThe Mass Distribution of sdB Stars Derived by Asteroseismology and Other Means: Implications for Stellar Evolution Theory
Van Grootel, Valérie ULg; Charpinet, Stéphane; Fontaine, Gilles et al

in Astronomical Society of the Pacific Conference Series (2014), 481

Understanding the formation of sdB stars is one of the remaining challenges of stellar evolution theory. Competing scenarios have been proposed to account for the existence of such evolved objects. They ... [more ▼]

Understanding the formation of sdB stars is one of the remaining challenges of stellar evolution theory. Competing scenarios have been proposed to account for the existence of such evolved objects. They give quite different mass distributions for resulting sdB stars. Detailed asteroseismic analyses, including mass estimates, of 15 pulsating hot B subdwarfs have been published in the past decade. Masses have also been reliably determined by light curve modeling and spectroscopy for 7 sdB components of eclipsing or reflection binaries. We present here the empirical mass distribution of sdB stars on the basis of these samples. Implications are also briefly discussed. [less ▲]

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See detailMASS LIMITS ON PARTICLES FROM PULSED SOURCES: HOW RELIABLE ARE THEY?
Cudell, Jean-René ULg; Halzen, F.; Hoyer, P.

in Phys. Rev. (1987), D36

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See detailMass Spectrometric determination of the Electronaffinities of Radicals.
Locht, Robert ULg; Momigny, Jacques

in Chemical Physics Letters (1970), 6(4), 273-276

By mass spectrometric study of the appearance of C2-, CH- and C2H- from CH4, C2H2, C2H4, C2H3X (X=F, Cl) the following electronaffinities have been determined: EA(CH)=(2.6+/-0.3) eV, EA(C2)=(3.3+/-0.2) eV ... [more ▼]

By mass spectrometric study of the appearance of C2-, CH- and C2H- from CH4, C2H2, C2H4, C2H3X (X=F, Cl) the following electronaffinities have been determined: EA(CH)=(2.6+/-0.3) eV, EA(C2)=(3.3+/-0.2) eV and EA(C2H)=(2.1+/-0.3) eV. Some evidence is brought to the existence of electronic excited states of these ions. An evaluation of these negative ions dissociation energy in their ground electronic state is given and is found to be of the order of magnitude of the corresponding isoelectronic molecular species dissociation energy. [less ▲]

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See detailA Mass Spectrometric Photoionization Study of CH3F. The CH2+, CH3+ and CH2F+ Ion Formation.
Locht, Robert ULg; Momigny, J.; Rühl, E. et al

in Chemical Physics (1987), 117

The decay of CH3F+ in the CH2+, CH3+ and CH2F+ dissociation channels has been investigated by photoionization mass spectrometry using synchrotron radiation in the energy range 10-25 eV. The ... [more ▼]

The decay of CH3F+ in the CH2+, CH3+ and CH2F+ dissociation channels has been investigated by photoionization mass spectrometry using synchrotron radiation in the energy range 10-25 eV. The photoabsorption curve of CH3F and the ionization efficiency curves of CH2+, CH3+ and CH2F+ as well as the kinetic energy-versus-appearance energy diagram for CH3+ were recorded. For the three fragment ions dissociative autoionization is a prominent formation process. Direct dissociative ionization is observed for the same ions through the decomposition of the CH3F+(A2A1+B2E) states at 16.1 eV as well as presumably of the C2A1 state at about 22.5 eV. [less ▲]

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See detailMass spectrometric sequencing of peptidic toxins : an overview
Quinton, Loïc ULg; Echterbille, Julien ULg; Pierre, Escoubas et al

in Editions de la SFET – SFET Editions (2010)

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See detailMass Spectrometric Study of Dissociative Attachment in Diatomic Molecules. II. NO and O2.
Locht, Robert ULg; Momigny, Jacques

in International Journal of Mass Spectrometry and Ion Physics (1970), 4

The DA processes of O- ions in NO and O2 are investigated using a 60° sector field mass spectrometer. In NO O- appears at (7.43+/-0.2) eV and the analysis of the DA curve indicates the probable existence ... [more ▼]

The DA processes of O- ions in NO and O2 are investigated using a 60° sector field mass spectrometer. In NO O- appears at (7.43+/-0.2) eV and the analysis of the DA curve indicates the probable existence of two other processes at 8.1 eV and 9.0 eV. In O2 only one process is observed at (3.45+/-0.3) eV. For both molecules an attempt is made to establish the shape of the potential energy curve of the electronic states of the transient negative molecular species involved. [less ▲]

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See detailMass Spectrometric Study of Dissociative Attachment in Diatomic Molecules:I. CO and H2
Locht, Robert ULg; Momigny, Jacques

in International Journal of Mass Spectrometry and Ion Physics (1969), 2

A study of the shape of the DA peaks leads to a general method for the determination of the threshold of a DA process. In order to test this method, the negative ions appearing in CO and H2 have been ... [more ▼]

A study of the shape of the DA peaks leads to a general method for the determination of the threshold of a DA process. In order to test this method, the negative ions appearing in CO and H2 have been investigated, using a sector field instrument. An attempt has been made to establish the relative positions of the potential energy curves (using the Morse function) for the electronic states involved in the processes observed [less ▲]

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See detailMass Spectrometric Study of Dissociative Electron Attachment in Carbon Dioxide.
Locht, Robert ULg; Momigny, Jacques

in Bulletin de la Société Royale des Sciences de Liège (1971), 40(9/10), 518-523

The DA efficiency curve of O- in CO2 has been studied mass spectrometricaly. Combining the use of the convolution of theoretical models and the deconvolution of the experimental curves, beside the ... [more ▼]

The DA efficiency curve of O- in CO2 has been studied mass spectrometricaly. Combining the use of the convolution of theoretical models and the deconvolution of the experimental curves, beside the previously reported DA peaks, some new DA processes have been determined at (6.0+/-0.3) eV and (13.3+/-0.4) eV for O- in CO2. A progressive conversion of electronic into vibrational excitation of diatomic radicals and into kinetic energy of the fragments is postulated as responsible for the threshold at (6.0+/-0.3) eV. [less ▲]

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See detailMass Spectrometric Study of Ion-Pair Processes in Diatomic Molecules: H2, CO, NO and O2.
Locht, Robert ULg; Momigny, Jacques

in International Journal of Mass Spectrometry and Ion Physics (1971), 7

The appearance of ion-pair processes has been studied in H2, CO, NO and O2. The different thresholds have been interpreted. Convolution and deconvolution techniques have been applied to the ionization ... [more ▼]

The appearance of ion-pair processes has been studied in H2, CO, NO and O2. The different thresholds have been interpreted. Convolution and deconvolution techniques have been applied to the ionization efficiency curves to determine (i) a method for the determination of the threshold energy and (ii) the kinetic energy distribution of the fragments. [less ▲]

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See detailMass Spectrometric Study of the Ionized C60: (Gamma-Cyclodextrin)2 Inclusion Complex by Collision Induced Dissociation
Greisch, Jean-François ULg; Kyritsoglou, S.; Leyh, Bernard ULg et al

in Journal of Mass Spectrometry [=JMS] (2008), 43(2), 242-50

The water soluble inclusion complex [C(60):(gamma-cyclodextrin)(2)] has been characterized using electrospray tandem mass spectrometry and collision induced dissociation. [C(60):(gamma-cyclodextrin)(2 ... [more ▼]

The water soluble inclusion complex [C(60):(gamma-cyclodextrin)(2)] has been characterized using electrospray tandem mass spectrometry and collision induced dissociation. [C(60):(gamma-cyclodextrin)(2)] ions were detected in the gas phase as doubly deprotonated, doubly protonated and doubly sodiated ions. The absence of monocharged complex ions following electronebulization is a likely consequence of the dimeric nature and structural symmetry of the inclusion complex. The collision induced dissociation of positive ions led exclusively to the observation of the protonated and sodiated cyclodextrin ions as well as their fragments. In negative ion mode the closed shell anion C(60)H(-) was the dominant fragment detected at low collision energies whereas at higher collision energies the signal corresponding to deprotonated cyclodextrin units becomes significant. Since C(60) (2-) has been reported to have a nonnegligible basicity compared to C(60) and C(60) (-), it is likely that the proton transfer involved in the formation of the C(60)H(-) anion occurs following transfer of the two electrons from the deprotonated gamma-cyclodextrins to the fullerene. Finally, the charge state of the inclusion complex ions is also shown to affect the interaction strengths between its subunits. The relative stabilities of the three ionic species studied in gas phase following electronebulization are as follows: [C(60):(gamma-cyclodextrin)(2) + 2H](2+) < [C(60):(gamma-cyclodextrin)(2)- 2H](2-) < [C(60):(gamma-cyclodextrin)(2) + 2Na](2+). [less ▲]

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See detailMass spectrometry and ion mobility spectrometry of G-quadruplexes. A study of solvent effects on dimer formation and structural transitions in the telomeric DNA sequence d(TAGGGTTAGGGT).
Ferreira, Ruben; Marchand, Adrien; Gabelica, Valérie ULg

in Methods (2012), 57(1), 56-63

We survey here state of the art mass spectrometry methodologies for investigating G-quadruplexes, and will illustrate them with a new study on a simple model system: the dimeric G-quadruplex of the 12-mer ... [more ▼]

We survey here state of the art mass spectrometry methodologies for investigating G-quadruplexes, and will illustrate them with a new study on a simple model system: the dimeric G-quadruplex of the 12-mer telomeric DNA sequence d(TAGGGTTAGGGT), which can adopt either a parallel or an antiparallel structure. We will discuss the solution conditions compatible with electrospray ionisation, the quantification of complexes using ESI-MS, the interpretation of ammonium ion preservation in the complexes in the gas phase, and the use of ion mobility spectrometry to resolve ambiguities regarding the strand stoichiometry, or separate and characterise different structural isomers. We also describe that adding electrospray-compatible organic co-solvents (methanol, ethanol, isopropanol or acetonitrile) to aqueous ammonium acetate increases the stability and rate of formation of dimeric G-quadruplexes, and causes structural transitions to parallel structures. Structural changes were probed by circular dichroism and ion mobility spectrometry, and the excellent correlation between the two techniques validates the use of ion mobility to investigate G-quadruplex folding. We also demonstrate that parallel G-quadruplex structures are easier to preserve in the gas phase than antiparallel structures. [less ▲]

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See detailMass spectrometry applied to biomolecules analysis
Far, Johann ULg; Mazzucchelli, Gabriel ULg; Meuwis, Marie-Alice ULg et al

Conference (2011, March 31)

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See detailMass spectrometry as a tool to search specific ligands for G protein coupled receptors.
Cologna, Camila Takeno; Echterbille, Julien ULg; De Pauw, Edwin ULg et al

Conference (2012)

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See detailMass spectrometry as an evolutive tool for toxinology: from sequencing to toxin shapes
Quinton, Loïc ULg; Gilles, Nicolas; Echterbille, Julien ULg et al

Conference (2011, September 12)

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See detailMass spectrometry imaging is moving toward drug protein co-localization
Ait-Belkacem, Rima; Sellami, Lyna; Villard, Claude et al

in Trends in Biotechnology (2012), 30(9), 466-474

Mass spectrometry (MS)-based technology provides label-free localization of molecules in tissue samples. Drugs, proteins, lipids and metabolites can easily be monitored in their environment. Resolution ... [more ▼]

Mass spectrometry (MS)-based technology provides label-free localization of molecules in tissue samples. Drugs, proteins, lipids and metabolites can easily be monitored in their environment. Resolution can be achieved down to the cellular level (10–20 mm) for conventional matrix-assisted laser desorption/ionization (MALDI) imaging, or even to the subcellular level for more complex technologies such as secondary ionization mass spectrometry (SIMS) imaging. One question remains: are we going to be able to investigate functional relationships between drugs and proteins and compare with localized phenomena? This review describes the various spatial levels of investigation offered by mass spectrometry imaging (MSI), and the advantages and disadvantages compared with other labeling technologies. [less ▲]

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See detailMass spectrometry imaging of rat brain sections: nanomolar sensitivity with MALDI versus nanometer resolution by TOF–SIMS
Benabdellah, Farida; Seyer, Alexandre; Quinton, Loïc ULg et al

in Analytical and Bioanalytical Chemistry (2010), 396(1), 151-162

Mass spectrometry imaging is becoming a more and more widely used method for chemical mapping of organic and inorganic compounds from various surfaces, especially tissue sections. Two main different ... [more ▼]

Mass spectrometry imaging is becoming a more and more widely used method for chemical mapping of organic and inorganic compounds from various surfaces, especially tissue sections. Two main different techniques are now available: matrix-assisted laser desorption/ionizaton, where the sample, preliminary coated by an organic matrix, is analyzed by a UV laser beam; and secondary ion mass spectrometry, for which the target is directly submitted to a focused ion beam. Both techniques revealed excellent performances for lipid mapping of tissue surfaces. This article will discuss similarities, differences, and specificities of ion images generated by these two techniques in terms of sample preparation, sensitivity, ultimate spatial resolution, and structural analysis. [less ▲]

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See detailMass Spectrometry lab activities in Liege - Small molecules
Focant, Jean-François ULg

Scientific conference (2012, March)

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See detailMass spectrometry of G-quadruplexes
Gabelica, Valérie ULg

Conference (2010, May 31)

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