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Peer Reviewed
See detailIon beam induced luminescence of minerals
Calvo Del Castillo, Helena ULg; Ruvalcaba Sil, Jose Luis; Calderón, Tomás

Poster (2006)

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See detailIon channel modulators: more diversity than previously thought
Dilly, Sébastien ULg; Lamy, Cédric; Marrion, Neil et al

in Chembiochem : A European Journal of Chemical Biology (2011), 12(12), 1808-1812

Ion channel function can be modified in various ways. For example, numerous studies have shown that currents through voltage-gated ion channels are affected by pore block or modification of voltage ... [more ▼]

Ion channel function can be modified in various ways. For example, numerous studies have shown that currents through voltage-gated ion channels are affected by pore block or modification of voltage-dependence of activation/inactivation. Recent experiments performed on various ion channels show that allosteric modulation is an important mechanism to affect channel function. For instance, in KCa2 (formerly SK) channels, the prototypic “blocker” apamin prevents conduction by an allosteric mechanism, while TRPV1 channels are prevented from closing by a tarantula toxin, DkTx, through an interaction with residues located away from the selectivity filter. The recent evidence therefore suggests that, in several ion channels, the region around the outer mouth of the pore is rich in binding sites which may be exploited therapeutically. These discoveries also suggest that the pharmacological vocabulary should be adapted to define these various actions. [less ▲]

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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 (in press)

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 – 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 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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See detailIon-beam analysis for cultural heritage on the AGLAE facility: impact of PIXE/RBS combination
Salomon, Joseph; Dran, Jean-Claude; Guillou, T. et al

in Applied Physics A : Materials Science & Processing (2008), 92(1), 43-50

The combination of particle-induced X-ray emission (PIXE) and Rutherford backscattering (RBS) is particularly fruitful for the study of cultural heritage objects. Several set-ups have been developed at ... [more ▼]

The combination of particle-induced X-ray emission (PIXE) and Rutherford backscattering (RBS) is particularly fruitful for the study of cultural heritage objects. Several set-ups have been developed at the AGLAE facility of the Louvre Laboratory to implement these techniques with an external beam. Successively have been tested the simultaneous use of PIXE and RBS with a single beam of protons, the sequential application of PIXE with protons and RBS with 4He2+ ions and finally the simultaneous implementation of PIXE and RBS with high-energy 4He2+ ions. Several examples illustrate the benefits of these combinations of techniques. [less ▲]

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See detailIon-exchange properties of polypyrrole doped by omega-carboxylated polyethyleneoxide
Jérôme, Christine ULg; Martinot, Lucien; Jérôme, Robert ULg

in Synthetic Metals (1999), 105(1), 65-71

α-Methoxy #969;-Na carboxylate polyethylenoxide (f-PEO) has been synthesized and used as counter-ion for the synthesis of polypyrrole (PPy) films. The effect of f-PEO concentration on the kinetics of ... [more ▼]

α-Methoxy #969;-Na carboxylate polyethylenoxide (f-PEO) has been synthesized and used as counter-ion for the synthesis of polypyrrole (PPy) films. The effect of f-PEO concentration on the kinetics of pyrrole polymerization has been studied. The ion exchange properties of the formed PPy/f-PEO composite have been analyzed in aqueous solution containing various salts (f-PEONa and LaCl3). The incorporation of indigo carmine in this type of composite has also been investigated. [less ▲]

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See detailIon-Mobility mass spectrometry as a potential tool to assign disulfide bonds arrangements in peptides with multiple disulfide bridges.
Echterbille, Julien ULg; Quinton, Loïc ULg; Gilles, Nicolas et al

in Analytical Chemistry (2013)

Disulfide bridges play a major role in defining the structural properties of peptides and proteins. However, the determination of the cysteine pairing is still challenging. Peptide sequences are usually ... [more ▼]

Disulfide bridges play a major role in defining the structural properties of peptides and proteins. However, the determination of the cysteine pairing is still challenging. Peptide sequences are usually achieved using MS/MS spectra of the totally reduced unfolded species but the cysteine pairing information is lost. On the other hand, MS/MS experiments performed on native folded species show complex spectra composed of non-classical ions. MS/MS alone does not allow the cysteine pairing nor the full sequence of an unknown peptide to be determined. The major goal of this work is to set up a strategy for the full structural characterization of peptides including disulfide bridges annotation in the sequence. This strategy was developed by combining Ion Mobility Spectrometry (IMS)and Collision Induced Dissociation(CID). It is assumed that the opening of one S-S bridges in a peptide leads to a structural evolution which results in a modification of IMS drift time. In the presence of multiple S-S bridges, the shift in arrival time will depend on which disulfide(s) has (have) been reduced and on the shape adopted by the generated species. Due to specific fragmentations observed for each species, CID experiments performed after the mobility separation could provide not only information on peptide sequence, but also on the localization of the disulfide bridges. To achieve this goal, synthetic peptides containing two disulfides were studied. The openings of the bridges were carried out following different experimental conditions such as reduction, reduction/alkylation or oxidation. Due to disulfide scrambling highlighted with the reduction approaches, oxidation of S-S bonds into cysteic acids appeared to be the best strategy. Cysteines connectivity was then unambiguously determined for the two peptides, without any disulfide scrambling interference. [less ▲]

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See detailIonic adsorption of ammonium and nitrate on some animal litters and their role in ammonia volatilization
Nimenya, H.; Delaunois, A.; Bloden, Serge ULg et al

in Annals of Zootechnology (2000), 49

Two experiments were carried out to determine the adsorption of ammonium and nitrate on litters (Exp. 1) and the volatilization of ammonia in their presence (Exp. 2). In Exp. 1, glass tubes containing 15 ... [more ▼]

Two experiments were carried out to determine the adsorption of ammonium and nitrate on litters (Exp. 1) and the volatilization of ammonia in their presence (Exp. 2). In Exp. 1, glass tubes containing 15 mi of a buffered solution enriched with NH4Clcalculated as 10.59 mg.l(-1) of NH4+ or KNO3 calculated as 50 mg.l(-1) of NO3- were used. Graded amounts (0 [control], 25, 50, 100 mg) of litters (wheat straw, nax straw (Equi-lin(R)), zeolite (Zeolite Stall Fresh(R)), spruce sawdust and beech sawdust) were added to the tubes which were incubated for 24 h. Ammonium and nitrate concentrations, and pH, were checked on the supernatant. A preliminary experiment was carried out with zeolite to come to an ammonium balance. After adsorption of ammoniumby graded amounts of zeolite, [0 (control), 0.25, 1, 2, 4 g], ammonium balance was assessed after two elutions with 1 N HCl. In Exp. 2, Woulff flasks were used and ammonia was trapped in a solution of 0.1 N HCl. The preliminary experiment showed that the ammonium added and adsorbed by different amounts of zeolite was completely recovered after 2 elutions. All litters, except beech sawdust, were effective in ammonium adsorption. Especially, the straws were required in very small amounts to immobilize the added ammonium or nitrate. Furthermore, with straws the pH value decreased from pH 7.5-7.60 to pH 6.90, and this effect was related to the amounts of material added. For each pH group, ammonia volatilization was significantly decreased (P <0.05) with straw (wheat straw, Equi-lino) as compared with their blank pH group. However, no significant decrease was observed with sawdust (spruce, beech) and zeolite [less ▲]

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