Records |
Author |
Dul, M.C.; Lescouezec, R.; Chamoreau, L.M.; Journaux, Y.; Carrasco, R.; Castellano, M.; Ruiz-Garcia, R.; Cano, J.; Lloret, F.; Julve, M.; Ruiz-Perez, C.; Fabelo, O.; Pardo, E. |
Title |
Self-assembly, metal binding ability, and magnetic properties of dinickel(II) and dicobalt(II) triple mesocates |
Type |
Journal Article |
Year |
2012 |
Publication |
CrystEngComm |
Abbreviated Journal |
CrystEngComm |
Volume |
14 |
Issue |
17 |
Pages |
5639-5648 |
Keywords |
|
Abstract |
Two metallacyclic complexes of general formula Na-8[(M2L3)-L-II]center dot xH(2)O [M = Ni (4) and Co (5) with x = 15 (4) and 17 (5)] have been self-assembled in aqueous solution from N,N'-1,3-phenylenebis(oxamic acid) (H4L) and M2+ ions in a ligand/metal molar ratio of 3 : 2 in the presence of NaOH acting as base. X-Ray structural analyses of 4 and 5 show triple-stranded, dinuclear anions of the meso-helicate-type (so-called mesocates) with C-3h molecular symmetry. The two octahedral metal-tris(oxamate) moieties of opposite chiralities (Delta, Lambda form) are connected by three m-phenylene spacers at intermetallic distances of 6.822(2) (4) and 6.868(2) angstrom (5) to give a metallacryptand core. In the crystal lattice, the binding of these heterochiral dinickel(II) and dicobalt(II) triple mesocates to sodium(I) ions leads to oxamato-bridged heterobimetallic three-dimensional open-frameworks with a hexagonal diamond architecture having small pores of 17.566(4) (4) and 17.640(2) angstrom (5) in diameter where the crystallization water molecules and the sodium(I) countercations are hosted. Variable temperature (2.0-300 K) magnetic susceptibility measurements reveal relatively anisotropic S = 2 Ni-2(II) (4) and S = 3 Co-2(II) (5) ground states resulting from the moderate to weak intramolecular ferromagnetic coupling between the two high-spin Ni-II (S-Ni = 1) or Co-II (S-Co = 3/2) ions across the m-phenylenediamidate bridges [J = +3.6 (4) and +1.1 cm(-1) (5); H = -JS(1)center dot S-2]. A simple molecular orbital analysis of the electron exchange interaction identifies the p-type pathways of the meta-substituted phenylene spacers involving the d(z2) and d(x2-y2) pairs of magnetic orbitals of the two trigonally distorted octahedral high-spin M-II ions (M = Ni and Co) as responsible for the overall ferromagnetic coupling observed in 4 and 5 in agreement with a spin polarization mechanism. The decrease of the overall ferromagnetic coupling from 4 to 5 is in turn explained by the additional antiferromagnetic exchange contribution involving the d(xy) pair of magnetic orbitals of the two trigonally distorted octahedral high-spin Co-II ions across the sigma-type pathway of the meta-substituted phenylene spacers. |
Address |
[Dul, Marie-Claire; Lescouezec, Rodrigue; Chamoreau, Lise-Marie; Journaux, Yves] Univ Paris 06, Inst Parisien Chim Mol, F-75005 Paris, France, Email: rodrigue.lescouezec@upmc.fr; |
Corporate Author |
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Thesis |
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Publisher |
Royal Soc Chemistry |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
|
ISSN |
1466-8033 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
|
Notes |
WOS:000306972100041 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
1125 |
Permanent link to this record |
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Author |
Casas, F.; Oteo, J.A.; Ros, J. |
Title |
Unitary transformations depending on a small parameter |
Type |
Journal Article |
Year |
2012 |
Publication |
Proceedings of the Royal Society A |
Abbreviated Journal |
Proc. R. Soc. A |
Volume |
468 |
Issue |
2139 |
Pages |
685-700 |
Keywords |
perturbation theory; quantum mechanics; unitary transformation; Magnus expansion |
Abstract |
We formulate a unitary perturbation theory for quantum mechanics inspired by the Lie-Deprit formulation of canonical transformations. The original Hamiltonian is converted into a solvable one by a transformation obtained through a Magnus expansion. This ensures unitarity at every order in a small parameter. A comparison with the standard perturbation theory is provided. We work out the scheme up to order ten with some simple examples. |
Address |
[Oteo, J. A.; Ros, J.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: rosj@uv.es |
Corporate Author |
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Thesis |
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Publisher |
Royal Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1364-5021 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000300185400005 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
no |
Call Number |
IFIC @ pastor @ |
Serial |
893 |
Permanent link to this record |
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Author |
Botella-Soler, V.; Valderrama, M.; Crepon, B.; Navarro, V.; Le Van Quyen, M. |
Title |
Large-Scale Cortical Dynamics of Sleep Slow Waves |
Type |
Journal Article |
Year |
2012 |
Publication |
Plos One |
Abbreviated Journal |
PLoS One |
Volume |
7 |
Issue |
2 |
Pages |
e30757 - 10pp |
Keywords |
|
Abstract |
Slow waves constitute the main signature of sleep in the electroencephalogram (EEG). They reflect alternating periods of neuronal hyperpolarization and depolarization in cortical networks. While recent findings have demonstrated their functional role in shaping and strengthening neuronal networks, a large-scale characterization of these two processes remains elusive in the human brain. In this study, by using simultaneous scalp EEG and intracranial recordings in 10 epileptic subjects, we examined the dynamics of hyperpolarization and depolarization waves over a large extent of the human cortex. We report that both hyperpolarization and depolarization processes can occur with two different characteristic time durations which are consistent across all subjects. For both hyperpolarization and depolarization waves, their average speed over the cortex was estimated to be approximately 1 m/s. Finally, we characterized their propagation pathways by studying the preferential trajectories between most involved intracranial contacts. For both waves, although single events could begin in almost all investigated sites across the entire cortex, we found that the majority of the preferential starting locations were located in frontal regions of the brain while they had a tendency to end in posterior and temporal regions. |
Address |
[Botella-Soler, Vicente] Univ Valencia, Dept Fis Teor, CSIC, Valencia, Spain, Email: quyen@t-online.de |
Corporate Author |
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Thesis |
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Publisher |
Public Library Science |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1932-6203 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000302853600065 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
986 |
Permanent link to this record |
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Author |
Valderrama, M.; Crepon, B.; Botella-Soler, V.; Martinerie, J.; Hasboun, D.; Alvarado-Rojas, C.; Baulac, M.; Adam, C.; Navarro, V.; Le Van Quyen, M. |
Title |
Human Gamma Oscillations during Slow Wave Sleep |
Type |
Journal Article |
Year |
2012 |
Publication |
Plos One |
Abbreviated Journal |
PLoS One |
Volume |
7 |
Issue |
4 |
Pages |
e33477 - 14pp |
Keywords |
|
Abstract |
Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS). At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30-50 Hz) and high (60-120 Hz) frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves (“IN-phase'' pattern), confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave (”ANTI-phase'' pattern). This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks. |
Address |
[Valderrama, Mario; Crepon, Benoit; Martinerie, Jacques; Hasboun, Dominique; Alvarado-Rojas, Catalina; Baulac, Michel; Adam, Claude; Navarro, Vincent; Le Van Quyen, Michel] Univ Paris 06, Ctr Rech Inst Cerveau & Moelle Epiniere CRICM, INSERM,UMRS 975, Hop La Pitie Salpetriere,CNRS,UMR 7225, Paris, France, Email: quyen@t-online.de |
Corporate Author |
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Thesis |
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Publisher |
Public Library Science |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1932-6203 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000304855200013 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
1058 |
Permanent link to this record |
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Author |
Botella-Soler, V.; Oteo, J.A.; Ros, J. |
Title |
Coexistence of periods in a bifurcation |
Type |
Journal Article |
Year |
2012 |
Publication |
Chaos, Solitons & Fractals |
Abbreviated Journal |
Chaos Solitons Fractals |
Volume |
45 |
Issue |
5 |
Pages |
681-686 |
Keywords |
|
Abstract |
A particular type of order-to-chaos transition mediated by an infinite set of coexisting neutrally stable limit cycles of different periods is studied in the Varley-Gradwell-Hassell population model. We prove by an algebraic method that this kind of transition can only happen for a particular bifurcation parameter value. Previous results on the structure of the attractor at the transition point are here simplified and extended. |
Address |
[Botella-Soler, V.; Oteo, J. A.; Ros, J.] Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain, Email: vicente.botella@uv.es |
Corporate Author |
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Thesis |
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Publisher |
Pergamon-Elsevier Science Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0960-0779 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000303785300014 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
no |
Call Number |
IFIC @ pastor @ |
Serial |
1005 |
Permanent link to this record |