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See detailIon Dissociation Kinetics in Mass Spectrometry
Leyh, Bernard ULg

in Reedijk, J. (Ed.) Reference Module in Chemistry, Molecular Sciences and Chemical Engineering (2013)

The variation of fragmentation rate constants as a function of the parent ion internal energy, or, alternatively, as a function of temperature, is crucial information to unravel the dissociation ... [more ▼]

The variation of fragmentation rate constants as a function of the parent ion internal energy, or, alternatively, as a function of temperature, is crucial information to unravel the dissociation mechanisms of molecular ions. This contribution provides the reader first with basic information on the statistical theories used to model unimolecular rate constants. Various experimental methods to measure such rate constants in the 102 to 1010 s^(-1) range are then discussed. Kinetic isotope effects are also briefly dealt with. How reaction mechanisms can be inferred from kinetic data is handled in an extensive section where selected examples from the recent literature are discussed. [less ▲]

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See detailIon homeostasis in the chloroplast
Hanikenne, Marc ULg; Bernal, Maria; Urzica, Eugen

in Wollman, Francis-Andre; Theg, Steve M. (Eds.) Plastid Biology (2014)

The chloroplast is an organelle of high demand for macro- and micro-nutrient ions, which are required for the maintenance of the photosynthetic process. To avoid deficiency while preventing excess ... [more ▼]

The chloroplast is an organelle of high demand for macro- and micro-nutrient ions, which are required for the maintenance of the photosynthetic process. To avoid deficiency while preventing excess, homeostasis mechanisms must be tightly regulated. Here, we describe the needs for nutrient ions in the chloroplast and briefly highlight their functions in the chloroplastidial metabolism. We further discuss the impact of nutrient deficiency on chloroplasts and the acclimation mechanisms that evolved to preserve the photosynthetic apparatus. We finally present what is known about import and export mechanisms for these ions. Whenever possible, a comparison between cyanobacteria, algae and plants is provided to add an evolutionary perspective to the description of ion homeostasis mechanisms in photosynthesis. [less ▲]

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See detailIon Mobility - Mass Spectrometry as a new approach for the screening of pesticide residues in food
Joly, Laure; Goscinny, Séverine ULg; Touilloux, Romain et al

Conference (2011, September)

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See detailIon Mobility Spectrometry Reveals Duplex DNA Dissociation Intermediates
Burmistrova, Anastasia; Gabelica, Valérie; Duwez, Anne-Sophie ULg et al

in Journal of the American Society for Mass Spectrometry (2013), 24

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See detailION MOBILITY – MASS SPECTROMETRY AS A NEW APPROACH FOR THE SCREENING OF PESTICIDE RESIDUES IN FOOD
Goscinny, Séverine ULg; Touilloux, Romain; Joly, Laure et al

in Organohalogen Compounds (2011)

Pesticide residue analysis requires methods that can determine hundreds of compounds at low levels in complex food matrices. This challenge has given rise to multi residue methods, the only efficient ... [more ▼]

Pesticide residue analysis requires methods that can determine hundreds of compounds at low levels in complex food matrices. This challenge has given rise to multi residue methods, the only efficient analytical approach. This type of analytical method entails a “generic” extraction followed by a soft or no purification step to avoid any analytes looses. With over a 1000 active compounds with different physical chemical properties, gas and liquid chromatography are used as complementary separative techniques. In the past decade, the determination has been performed on tandem mass analyzers, a powerful tool to overcome co-eluting compounds with excellent sensitivity. Nevertheless, these instruments can guarantee these results per acquisition cycles for more or less 150 compounds. This represents a serious limitation when the number of pesticides to be sought for monitoring and MRL enforcement is growing each year. As multiple injections from the same sample are not viable for laboratories, alternative options have to be explored. We propose the investigation of ion mobility (IM) coupled with mass spectrometry as a new approach for pesticide residue analysis in food. [less ▲]

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See detailIon mobility-mass spectrometry to perform structural classifications of disulfide-bridged-peptides
Massonnet, Philippe ULg; Upert, Gregory; Morsa, Denis ULg et al

Poster (2014, November)

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See detailIon outflow observed by IMAGE: Implications for source regions and heating mechanisms
Fuselier, S. A.; Ghielmetti, A. G.; Moore, T. E. et al

in Geophysical Research Letters (2001), 28

Images of the Earth's proton aurora from the IMAGE spacecraft on 8 June 2000 indicate a temporally and spatially isolated ionospheric response to a shock that impinged on the Earth's magnetopause ... [more ▼]

Images of the Earth's proton aurora from the IMAGE spacecraft on 8 June 2000 indicate a temporally and spatially isolated ionospheric response to a shock that impinged on the Earth's magnetopause. Sometime after this ionospheric response, the Low Energy Neutral Atom imager on IMAGE detected enhanced ionospheric outflow. The time delay between the ionospheric response and the enhanced outflow is consistent with the travel time of ~30 eV neutral Oxygen (created by charge exchange of outflowing O[SUP]+[/SUP] with the exosphere) from the low altitude ionosphere to the spacecraft. The prompt ionospheric outflow implies that the shock deposited sufficient energy in the topside ionosphere near or above the O[SUP]+[/SUP] exobase to initiate the outflow. [less ▲]

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See detailAn Ion Retarding Potential Difference Method applied to Dissociative Photoionization Mass Spectrometry.
Locht, Robert ULg; Rühl, E.; Hagenow, G. et al

in Dalgarno, A.; Freund, R. S.; Lubell, M. S. (Eds.) et al 16th International Conference on the Physics of Electronic and Atomic Collisions: Abstract of Contributed Papers. (1989)

Dissociative photoionization of O2 has been investigated by using the ion retarding potential for the translational energy analysis of the O+ fragment. Synchrotron radiation is used as a light source ... [more ▼]

Dissociative photoionization of O2 has been investigated by using the ion retarding potential for the translational energy analysis of the O+ fragment. Synchrotron radiation is used as a light source. Ionization efficiency curves have been recorded at several retarding potential settings. [less ▲]

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See detailIon Translational Energy Distributions from Inner-shell Dissociative ionization of N2O, NH3 and SF6.
Locht, Robert ULg; Leyh, Bernard ULg; Jochims, H. W. et al

Book published by Berliner Elektronen Speicherring für Synchrotron Strahlung m.b.H (1992)

The IRPD method is applied to the dissociative ionization in the inner-shell ionization region for NO+, N2+, O+, N+ and N++/N2O. Particular attention has been focussed on the production and ion kientic ... [more ▼]

The IRPD method is applied to the dissociative ionization in the inner-shell ionization region for NO+, N2+, O+, N+ and N++/N2O. Particular attention has been focussed on the production and ion kientic energy distribution of H+/NH3. [less ▲]

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See detailIon Traps and Lifetime Calculations in Yb II
Biémont, Emile ULg; Dutrieux, J.-F.; Martin, I. et al

Conference (1998, August)

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See detailIon- and dust-acoustic solitons in dusty plasmas: Existence conditions for positive and negative potential solutions
Verheest, F.; Cattaert, Tom ULg; Hellberg, M. A.

in Physics of Plasmas (2005), 12(8), 8

The usual description of dust-modified ion-acoustic and dust-acoustic solitons in plasmas containing negative dust is in terms of Boltzmann distributions for the hotter species. In the dust-modified ion ... [more ▼]

The usual description of dust-modified ion-acoustic and dust-acoustic solitons in plasmas containing negative dust is in terms of Boltzmann distributions for the hotter species. In the dust-modified ion-acoustic regime, besides positive potential solitons, negative structures can also be generated, for electrons with a polytropic index gamma(e)not equal 1, as well as for Boltzmann electrons, subject to conditions that are not too stringent. These general conditions were previously either ignored or given for weakly nonlinear solutions only. In the dust-acoustic domain in plasmas with negatively charged dust, however, only negative potential solitons can occur, even when the lighter species have non-Boltzmann distributions. For Boltzmann electrons only an infinite dust compression limits the soliton amplitudes and corresponding Mach numbers, whereas for gamma(e)not equal 1, the electron density, too, can be a limiting factor for the existence domain of such solitons. (c) 2005 American Institute of Physics. [less ▲]

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