| 1. |
- Bergshoeff, E. A., et al.
(författare)
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E10 and gauged maximal supergravity
- 2009
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2009:1, s. 020 (artno)-
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Tidskriftsartikel (refereegranskat)abstract
- We compare the dynamics of maximal three-dimensional gauged supergravity in appropriate truncations with the equations of motion that follow from a one-dimensional E10/K(E-10) coset model at the first few levels. The constant embedding tensor, which describes gauge deformations and also constitutes an M-theoretic degree of freedom beyond eleven-dimensional supergravity, arises naturally as an integration constant of the geodesic model. In a detailed analysis, we find complete agreement at the lowest levels. At higher levels there appear mismatches, as in previous studies. We discuss the origin of these mismatches.
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| 2. |
- Stuhr-Hansen, Nicolai, et al.
(författare)
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Organoselenium-Substituted Poly(p-phenylenevinylene)
- 2005
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Ingår i: Heteroatom Chemistry. - : Wiley. - 1042-7163 .- 1098-1071. ; 16:7, s. 656-662
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Tidskriftsartikel (refereegranskat)abstract
- A new type of conjugated polymer, organoselenium substituted poly(p-pheylenevinylene) (PPV), was synthesized from the corresponding alkylselenenyl p-xylylene dibromide via a Gilch route using potassium tert-butoxide in THF. The p-xylylene dibromide precursors were synthesized by reacting lithiated bis(methoxymethyl)benzenes with elemental selenium, followed by alkylation of the generated selenolates. As a final demasking step, the bromomethyl functions were liberated by ether cleavage using boron tribromide. Bis-alkylselenenyl PPV was obtained with an average molecular weight Mw of approximately 300,000 g/mol and with polydispersity Mw/Mn=2. Due to low solubility, monoalkylselenenyl PPV was obtained with a considerably lower average molecular weight in the proximity of 16,000 g/mol and with a polydispersity slightly larger than 3. Absorption and flourescence spectroscopy revealed that the bis-alkylselenenyl PPV is extensively conjugated.
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