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See detailCharge distribution in 3'-deoxythymidine-fullerene: Mass spectrometry, laser excitation, and computational studies
Greisch, Jean-François ULg; Weinkauf, R.; De Pauw, Edwin ULg et al

in Israel Journal of Chemistry (2007), 47(1), 25-35

Electrospray ionization of the donor-spacer-acceptor model system 3'-imino[60]fulleryl-3'-deoxythymidine molecule (FdT) produces deprotonated negatively charged species (dFdT). In this paper, we ... [more ▼]

Electrospray ionization of the donor-spacer-acceptor model system 3'-imino[60]fulleryl-3'-deoxythymidine molecule (FdT) produces deprotonated negatively charged species (dFdT). In this paper, we investigate where the negative charge is localized and whether its location can be manipulated. The fragmentation of dFdT is studied experimentally by mass spectrometry using both collisional and photoactivation. Besides fragmentation, photoexcitation of anions stored in an ion trap leads to electron photodetachment. The competition between the two channels is studied as a function of the excitation wavelength. Starting from the neutral parents, two families of dFdT molecules are computationally identified. Deprotonation takes place on the 3'-deoxythymidine (dT) subunit, either on the thymine at N3 or on the deoxyribose residue at O5'. Deprotonation in N3 leads to negatively charged molecules with an extended geometry and the excess charge largely localized on the dT. The O5'-deprotonation leads to lower-energy folded conformers stabilized by an additional bond (C-O or C-H) with the nearby C-60-N acceptor part, and the negative charge is mostly localized on the fullerene. The calculated electron detachment energies are higher for the extended N3dFdT conformers than for the O5'dFdT ones. Multiphoton photodetachment experiments at 1064 nm indicate the negative charge to be on the C-60 unit. No indication for a photoinduced charge transfer was found. In MS beside the C-60 anion a C60NH, - fragment is observed, which implies a double intramolecular H transfer. The computed energy of the corresponding dFdT, stabilized by two H-C-60 bonds, is intermediate between N3 and O5' deprotonated molecules. [less ▲]

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See detailCharge et modalité : apport ou transfert dans une structure patrimoniale
Dehalleux, Virginie ULg

in Leleu, Yves-Henri; Verbeke, Alain; Taymans, Jean-François (Eds.) et al Manuel de planification patrimoniale (in press)

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See detailCharge et modalité : interdiction de partager (maintien en indivision)
Dehalleux, Virginie ULg

in Leleu, Yves-Henri; Verbeke, Alain; Taymans, Jean-François (Eds.) et al Manuel de planification patrimoniale (2010)

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See detailCharge et modalité : rente périodique au profit d'un tiers
Dehalleux, Virginie ULg

in Leleu, Yves-Henri; Verbeke, Alain; Taymans, Jean-François (Eds.) et al Manuel de Planification patrimoniale (2010)

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See detailCharge et modalité : rente périodique au profit d'un tiers - indexation/plafond
Dehalleux, Virginie ULg

in Leleu, Yves-Henri; Verbeke, Alain; Taymans, Jean-François (Eds.) et al Manuel de planification patrimoniale (2010)

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See detailCharge et modalité : soins, logement et entretien d'un tiers
Dehalleux, Virginie ULg

in Leleu, Yves-Henri; Verbeke, Alain; Taymans, Jean-François (Eds.) et al Manuel de planification patrimoniale (2010)

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See detailCharge exchange in tandem mass spectrometry: dissociative single electron capture by doubly-charged toluene cations
Fati, D.; Leyh, Bernard ULg

in European Journal of Mass Spectrometry (Chichester, England) (2003), 9(4), 223-235

Single electron capture by doubly-charged toluene cations upon collision with various target gases has been investigated by sector tandem mass spectrometry. Both non-dissociative and dissociative charge ... [more ▼]

Single electron capture by doubly-charged toluene cations upon collision with various target gases has been investigated by sector tandem mass spectrometry. Both non-dissociative and dissociative charge transfer reactions leading to C(7)H(7)(+) + H and to C(5)H(5)(+) + [C(2),H(3)] are detected. Seven atomic or molecular target gases have been used with ionisation energies ranging from 8.8 eV to 14 eV. The branching ratios between the different non-dissociative and dissociative exit channels have been determined as well as the translational energy release on the dissociation products. The experimental data are compared to the predictions of a two-state semi-classical theoretical model that takes into account the non-adiabatic transition responsible for the charge transfer reaction. A wide reaction window shows up but the internal energies of the C(7)H(8)(+) cations produced by single electron capture are observed to be larger than expected. We assign this effect partly to the influence of the large density of vibrational states and to the multichannel nature of the process. Excited states of the dication are also most probably involved in the charge exchange reaction. [less ▲]

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See detailCharge Migration in the Bifunctional PENNA Cation Induced and Probed by Ultrafast Ionization: A Dynamical Study.
Mignolet, Benoît ULg; Levine, R. D.; Remacle, Françoise ULg

in Journal of Physics : B Atomic Molecular & Optical Physics (2014), 47

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See detailCharge Order in LuFe2O4: Antiferroelectric Ground State and Coupling to Magnetism
Angst, M.; Hermann, Raphaël ULg; Christianson, A. D. et al

in Physical Review Letters (2008), 101(22),

X- ray scattering by multiferroic LuFe2O4 is reported. Below 320 K, superstructure reflections indicate an incommensurate charge order with propagation close to (1/3 1/3 3/2). The corresponding charge ... [more ▼]

X- ray scattering by multiferroic LuFe2O4 is reported. Below 320 K, superstructure reflections indicate an incommensurate charge order with propagation close to (1/3 1/3 3/2). The corresponding charge configuration, also found by electronic structure calculations as most stable, contains polar Fe= O double layers with antiferroelectric stacking. Diffuse scattering at 360 K, with (1/3 1/3 0) propagation, indicates ferroelectric short- range correlations between neighboring double layers. The temperature dependence of the incommensuration indicates that charge order and magnetism are coupled. [less ▲]

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See detailCharge order superstructure with integer iron valence in Fe2OBO3
Angst, M.; Khalifah, P.; Hermann, Raphaël ULg et al

in Physical Review Letters (2007), 99(8),

Solution-grown single crystals of Fe2OBO3 were characterized by specific heat, Mossbauer spectroscopy, and x-ray diffraction. A peak in the specific heat at 340 K indicates the onset of charge order ... [more ▼]

Solution-grown single crystals of Fe2OBO3 were characterized by specific heat, Mossbauer spectroscopy, and x-ray diffraction. A peak in the specific heat at 340 K indicates the onset of charge order. Evidence for a doubling of the unit cell at low temperature is presented. Combining structural refinement of diffraction data and Mossbauer spectra, domains with diagonal charge order are established. Bond-valence-sum analysis indicates integer valence states of the Fe ions in the charge ordered phase, suggesting Fe2OBO3 is the clearest example of ionic charge order so far. [less ▲]

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See detailCharge Order, Dynamics, and Magnetostructural Transition in Multiferroic LuFe2O4
Xu, X. S.; Angst, M.; Brinzari, T. V. et al

in Physical Review Letters (2008), 101(22),

We investigated the series of temperature and field-driven transitions in LuFe2O4 by optical and Mossbauer spectroscopies, magnetization, and x-ray scattering in order to understand the interplay between ... [more ▼]

We investigated the series of temperature and field-driven transitions in LuFe2O4 by optical and Mossbauer spectroscopies, magnetization, and x-ray scattering in order to understand the interplay between charge, structure, and magnetism in this multiferroic material. We demonstrate that charge fluctuation has an onset well below the charge ordering transition, supporting the "order by fluctuation" mechanism for the development of charge order superstructure. Bragg splitting and large magneto-optical contrast suggest a low-temperature monoclinic distortion that can be driven by both temperature and magnetic field. [less ▲]

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See detailCharge transfer complex inimer: A facile route to dendritic materials
Wang, Wenxin; Yan, Deyue; Bratton, Daniel et al

in Advanced Materials (2003), 15(16), 1348-1352

A versatile approach to the preparation of hyperbranched polymers, in which an inimer is used to assemble a charge transfer complex (CTC) with conventional vinyl monomers, is reported. A novel ... [more ▼]

A versatile approach to the preparation of hyperbranched polymers, in which an inimer is used to assemble a charge transfer complex (CTC) with conventional vinyl monomers, is reported. A novel hyperbranched fluoro-polymer (see Figure) has been successfully synthesized through the copolymerization of chlorotrifluoroethylene (CTFE) and p-(chloromethyl)styrene (CMS) by atom transfer radical polymerization (ATRP). [less ▲]

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See detailCharge transfer study through the determination of the ionization energies of tetrapeptides X3-Tyr, X = Gly, Ala, or Leu. Influence of the inclusion of one glycine in alanine and leucine containing peptides
Dehareng, Dominique ULg; Dive, Georges ULg

in Journal of Physical Chemistry A (2006), 110(43), 11975-11987

The energies of the fundamental and several excited states of tetrapeptide radical cations were determined at the outer valence Green's function (OVGF) level, at three geometries corresponding to the ... [more ▼]

The energies of the fundamental and several excited states of tetrapeptide radical cations were determined at the outer valence Green's function (OVGF) level, at three geometries corresponding to the lowest energy conformations: two for the neutral and one for the cation. The conformations were optimized at the density functional theory level within the B3LYP framework. It was found that, from a purely energetic point of view, a charge initially created on the tyrosine chromophore could migrate without any geometrical change and without further activation once the excited electronic state of the ionized chromophore was formed. This migration could reach the NH2 terminus for the neutral conformations but should stop at the adjacent peptide link for the cation conformation. These results stress the probable influence of the electronic coupling between the states rather than the existence of a barrier on the charge pathway to explain the difference between the peptides in the charge-transfer process leading to the loss of an iminium [NH2 = CHR](+) cation. The dissociation energy of the asymptote related to the formation of this NH2 terminus iminium cation was calculated for few species and it appears that the excess energy available for dissociation is significant when starting from the lowest energy conformations of the neutral or the cation, provided that the charge transfer is effective. It was also found that the amino acids did not conserve their energetic properties and their zero order energy levels turned to a complete new energetic scheme corresponding to the conformation of the peptide. [less ▲]

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See detailLa charge vocale : De sa quantification à l’étude de son impact sur la fonction phonatoire et sur la qualité vocale
Remacle, Angélique ULg

Doctoral thesis (2013)

Ce travail étudie la charge vocale principalement chez les enseignants. La prévalence élevée des troubles de la voix chez ces professionnels serait en partie liée aux trois facteurs principaux de charge ... [more ▼]

Ce travail étudie la charge vocale principalement chez les enseignants. La prévalence élevée des troubles de la voix chez ces professionnels serait en partie liée aux trois facteurs principaux de charge vocale que sont la durée de phonation, le niveau de pression sonore, et la fréquence vocale. Ces facteurs sont associés à des contraintes mécaniques appliquées aux plis vocaux lors de la vibration, potentiellement responsables de microtraumatismes du tissu, et participant au développement de lésions bénignes. Notre contribution intervient à deux niveaux d’étude de la charge vocale. Dans un premier temps, nous l’avons quantifiée en situation écologique dans une population d’enseignantes, en comparant deux niveaux de l’enseignement ordinaire belge : le maternel et le primaire. A cette fin, le comportement vocal de 12 enseignantes du maternel et de 20 enseignantes du primaire a été enregistré durant une semaine de travail, à l’aide d’un système de dosimétrie. Les objectifs étaient, d’une part, de déterminer les différences d’utilisation vocale selon le niveau d’enseignement, et d’autre part, de comparer l’utilisation vocale professionnelle et extra-professionnelle des enseignantes. Globalement, nos résultats montrent une charge vocale plus élevée en situation professionnelle qu’en situation extra-professionnelle. Par ailleurs, les enseignantes du maternel présentent une charge vocale plus élevée que celles du primaire, en termes de nombre de cycles vibratoires et de distance parcourue par les plis vocaux. Dans un deuxième temps, nous avons étudié l’impact de la charge vocale sur la fonction phonatoire et sur la qualité vocale en condition de laboratoire. Une première condition expérimentale avait pour but d’améliorer la compréhension des facteurs de durée et d’intensité de la charge vocale, en soumettant 50 femmes normophoniques à 2 heures de charge, réalisées à deux reprises en variant le niveau d’intensité. Une seconde condition expérimentale avait pour but de comparer les effets de 2 heures de charge chez 16 enseignantes normophoniques et 16 enseignantes dysphoniques. Les effets de la charge vocale ont été évalués à l’aide de mesures objectives et subjectives. Les principaux résultats montrent plus d’impact de la durée que de l’intensité de la charge sur les paramètres observés. Par ailleurs, peu de différences sont observées entre les deux groupes d’enseignantes au cours de la tâche de charge, suggérant que les enseignantes dysphoniques présentent une bonne résistance durant la charge. [less ▲]

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See detailLa charge vocale dans l’évaluation et le traitement de la dysphonie
Remacle, Angélique ULg; Morsomme, Dominique ULg

in Actes du 26e Congrès Scientifique International de la Fédération Nationale des Orthophonistes (in press)

Voice problems can be triggered by both vocal misuse and overuse. While misuse is caused by inappropriate vocal actions, overuse results from greater vocal loading than the individual is able to recover ... [more ▼]

Voice problems can be triggered by both vocal misuse and overuse. While misuse is caused by inappropriate vocal actions, overuse results from greater vocal loading than the individual is able to recover from. Vocal load depends primarily on the quantity of phonation in terms of duration, fundamental frequency and sound pressure of the voice. Portable load quantification systems have been available for several years. These dosimeters allow the objective description of vocal behavior in real situations for a prolonged duration. They are primarily used by voice professionals – people who need their voices for their work – such as teachers and singers. Voice dosimetry makes it possible to identify risky vocal behaviors and situations promoting dysphonia, in an ecological context. The objective of research using these tools is to suggest guidelines for the prevention, evaluation and treatment of dysphonia, mainly in people who use their voices a lot. In addition, this research attempts to set standards for daily voice use for different groups of individuals. [less ▲]

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See detailLa charge vocale et son incidence sur le traitement orthophonique
Remacle, Angélique ULg

Scientific conference (2014, December 17)

Les troubles de la voix peuvent être engendrés tant par un malmenage que par un surmenage vocal. Tandis que le malmenage est causé par un geste vocal inadéquat, le surmenage résulte d’une charge vocale ... [more ▼]

Les troubles de la voix peuvent être engendrés tant par un malmenage que par un surmenage vocal. Tandis que le malmenage est causé par un geste vocal inadéquat, le surmenage résulte d’une charge vocale supérieure aux capacités de récupération de l’individu. Dans cet atelier, nous expliquerons ce qu’est la charge vocale, nous la replacerons dans le contexte des stress mécaniques appliqués aux plis vocaux lors de la phonation et nous exposerons les conséquences d’une surcharge vocale. Nous présenterons ensuite les systèmes portables de monitoring de la voix commercialisés depuis quelques années : les dosimètres ou accumulateurs de voix. Ces outils permettent d’objectiver le comportement vocal en situation réelle pendant une durée prolongée et aident à cibler les situations favorisant la dysphonie. Enfin, nous discuterons des apports du feedback vibratoire dans le but de modifier le comportement vocal en temps réel. [less ▲]

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See detailLa charge vocale et son incidence sur le traitement orthophonique
REMACLE, Angélique ULg; Morsomme, Dominique ULg

Conference (2013, October 25)

Detailed reference viewed: 64 (15 ULg)
See detailLa charge vocale
REMACLE, Angélique ULg; Morsomme, Dominique ULg

Conference (2014, March 29)

Detailed reference viewed: 47 (3 ULg)