Search results for "complex"
showing 10 items of 5889 documents
Les différentes formes de complexité des systèmes de risque et de catastrophe
2007
International audience
Analyser les catastrophes : une approche par les comportements humains
2011
La catastrophe est une forme de crise qui altère profondément un système social soumis à une situation de stress collectif. Ce dernier est confronté à une agression qui surpasse ses capacités d'adaptation induisant une désorganisation sociale et territoriale plus ou moins longue. L'environnement physique, qui influe peu sur les comportements observés en situation normale, contrairement à l'environnement social, impose de nouvelles façons d'agir, de nouveaux modes d'organisation, quelles que soient les échelles considérées. Il s'agit au moment du choc d'assurer sa survie et celle de ses proches (à condition qu'ils ne soient pas trop éloignés spatialement), puis une fois le danger écarté, de …
Repression of Human Papillomavirus Oncogene Expression under Hypoxia Is Mediated by PI3K/mTORC2/AKT Signaling
2019
Oncogenic HPV types are major human carcinogens. Under hypoxia, HPV-positive cancer cells can repress the viral E6/E7 oncogenes and induce a reversible growth arrest. This response could contribute to therapy resistance, immune evasion, and tumor recurrence upon reoxygenation. Here, we uncover evidence that HPV oncogene repression is mediated by hypoxia-induced activation of canonical PI3K/mTORC2/AKT signaling. AKT-dependent downregulation of E6/E7 is only observed under hypoxia and occurs, at least in part, at the transcriptional level. Quantitative proteome analyses identify additional factors as candidates to be involved in AKT-dependent E6/E7 repression and/or hypoxic PI3K/mTORC2/AKT ac…
Second thoughts about social complexity developments in Western Mediterranean valleys
2005
El artículo se centra en descubrimientos recientes en algunos valles de la costa española del Mediterráneo central, donde los nuevos datos nos permiten proponer diferentes caminos hacia la complejidad social. Varias zanjas monumentales que datan de ca. 5500 cal BP en diferentes sitios, pero particularmente en el sitio de Mas D’Is han abierto nuevas preguntas sobre cómo La literatura arqueológica ha presentado complejidad social en la Península Ibérica. Tradicionalmente, las sociedades complejas se han asociado con el desarrollo de la metalurgia y los sitios monumentales como Los Millares o Zambujal fueron el centro del debate. Sin embargo, los recientes desarrollos teóricos fuera de la disc…
Coordination chemistry on surfaces through vapor phase processing: smart molecular/graphene heterostructures based on spin-crossover complexes and 2D…
2023
Los compuestos de coordinación están últimamente focalizando la atención de los investigadores en el campo de la nanociencia. Particular interés están generando aquellos compuestos con propiedades magnéticas de cara a su integración a la nanoescala en ramas como la electrónica y/o la espintrónica moleculares. Sin embargo, para su uso real en dispositivos destinados a estas aplicaciones, su procesabilidad es un requisito indispensable. En el marco de esta necesidad, la presente tesis doctoral se ha destinado al estudio del procesado sobre superficies mediante técnicas de fase gas de dos tipos distintos de compuestos de coordinación. Por tanto, el trabajo se ha dividido en dos partes. La prim…
Die Komplexchemie niederer Schwefeloxide, IV ESCA-Untersuchungen an S2-, S2O- und S202 -Komplexen des Iridiums / The Complex Chemistry of Low Sulfuro…
1977
The ESCA spectra of the complexes [(TPE)2Ir(S2)]Cl, [(TPE)2Ir(S2O)]PF6 and [(TPE)2Ir(S2O2)]Cl, (TPE = Ph2P(CH2)2PPh2, “diphos”), have been investigated. The binding energy data for the S 2p, Ir 4f and P 2p electrons were measured and are discussed.
Relationship between Electron Affinity and Half-Wave Reduction Potential: A Theoretical Study on Cyclic Electron-Acceptor Compounds.
2016
A high-level ab initio protocol to compute accurate electron affinities and half-wave reduction potentials is presented and applied for a series of electron-acceptor compounds with potential interest in organic electronics and redox flow batteries. The comprehensive comparison between the theoretical and experimental electron affinities not only proves the reliability of the theoretical G3(MP2) approach employed but also calls into question certain experimental measurements, which need to be revised. By using the thermodynamic cycle for the one-electron attachment reaction A+e- →A- , theoretical estimates for the first half-wave reduction potential have been computed along the series of ele…
Achieving Strong Positive Cooperativity through Activating Weak Non-Covalent Interactions
2018
Positive cooperativity achieved through activating weak non-covalent interactions is common in biological assemblies but is rarely observed in synthetic complexes. Two new molecular tubes have been synthesized and the syn isomer binds DABCO-based organic cations with high orientational selectivity. Surprisingly, the ternary complex with two hosts and one guest shows a high cooperativity factor (α=580), which is the highest reported for synthetic systems without involving ion-pairing interactions. The X-ray single-crystal structure revealed that the strong positive cooperativity likely originates from eight C-H⋅⋅⋅O hydrogen bonds between the two head-to-head-arranged syn tube molecules. Thes…
2017
Eight coordination compounds of formulae [FeII(L˙)2][ReIVCl6] (1a), [FeII(L˙)2][ReIVBr6] (1b), [CoII(L˙)2][ReIVCl6]·CH3CN (2a), [CoII(L˙)2][ReIVBr6] (2b), [NiII(L˙)(CH3CN)3][ReIVCl6]·CH3CN (3a), [NiII(L˙)(CH3CN)3][ReIVBr6]·3CH3CN (3b), [CuII(L˙)2][ReIVCl6] (4a) and [CuII(L˙)2][ReIVBr6] (4b), where L˙ is the aminoxyl radical chelating ligand, 4,4′-dimethyl-2,2′-di(2-pyridyl)oxazolidine-N-oxide, have been synthesised. Structural and magnetic studies reveal metal–radical intramolecular antiferromagnetic interactions in the [MII(L˙)2]2+ cations in the iron, cobalt and copper based compounds (1a, 1b, 2a, 2b, 4a and 4b) with the central metal ion low-spin in the case of iron (1a and 1b) and a gra…
A nucleophilic gold complex.
2019
Solid-state auride salts featuring the negatively charged Au– ion are known to be stable in the presence of alkali metal counterions. While such electron-rich species might be expected to be nucleophilic (in the same manner as I–, for example), their instability in solution means that this has not been verified experimentally. Here we report a two-coordinate gold complex (NON)AlAuPtBu3 (where NON is the chelating tridentate ligand 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) that features a strongly polarized bond, Auδ––Alδ+. This is synthesized by reaction of the potassium aluminyl compound [K{Al(NON)}]2 with tBu3PAuI. Computational studies of the complex, includ…