The Experts below are selected from a list of 119409 Experts worldwide ranked by ideXlab platform
Cornelia Vizman - One of the best experts on this subject based on the ideXlab platform.
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universal central extension of the lie algebra of hamiltonian vector fields
International Mathematics Research Notices, 2016Co-Authors: Bas Janssens, Cornelia VizmanAbstract:For a connected symplectic manifold X, we determine the universal central extension of the Lie algebra ham(X) of hamiltonian vector fields. We classify the central extensions of ham(X), of the Lie algebra sp(X) of symplectic vector fields, of the Poisson Lie algebra C 1 (X), and of its compactly Supported Version C 1 c (X).
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universal central extension of the lie algebra of hamiltonian vector fields
arXiv: Symplectic Geometry, 2015Co-Authors: Bas Janssens, Cornelia VizmanAbstract:We determine the universal central extension of the Lie algebra of hamiltonian vector fields, thereby classifying its central extensions. Furthermore, we classify the central extensions of the Lie algebra of symplectic vector fields, of the Poisson Lie algebra, and of its compactly Supported Version.
Franco Cozzi - One of the best experts on this subject based on the ideXlab platform.
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immobilization of organic catalysts when why and how
Advanced Synthesis & Catalysis, 2006Co-Authors: Franco CozziAbstract:This review article is divided in two parts. In the first part (Sections 2 and 3) selected examples of the publications that appeared in the literature in the period 2003-2005 in the field of immobilized organic catalysis are presented. When appropriate, the results of these publications are compared to those reported earlier and already discussed in a previous review article (see ref. [4] ). On the basis of this survey, in Section 4 some general considerations about when and why a Supported Version of an organic catalyst is worth developing are proposed. In Section 4 a list of suggestions about how the process of immobilization should be carried out is also included, taking into account several factors such as the properties of the catalyst, the nature of the support, and the mode of connection of the catalyst to the support.
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enantioselective 1 3 dipolar cycloadditions of unsaturated aldehydes promoted by a poly ethylene glycol Supported organic catalyst
ChemInform, 2004Co-Authors: Alessandra Puglisi, Franco Cozzi, Maurizio Benaglia, Mauro Cinquini, Giuseppe CelentanoAbstract:We have developed a polymer-Supported Version of MacMillan’s catalyst by anchoring a tyrosine-derived imidazolidin-4-one by means of a spacer to the monomethyl ether of poly(ethylene glycol) (MW = 5000 Da). The Supported organic catalyst was employed in some 1,3-dipolar cycloadditions involving α,β-unsaturated aldehydes and nitrones. The products were obtained in enantiomeric excesses very similar to those observed with the non-Supported catalyst, but the chemical yields were somewhat lower. Exploiting the solubility profile of the polymeric support, the catalyst was readily separated from the reaction products, recovered, and recycled. Catalyst recycling was accompanied by a very marginal erosion (if any) of the enantioselectivity and a more-substantial decrease in chemical efficiency. We ascribe the latter phenomenon mainly to the intrinsic instability of the catalyst under the reaction conditions, which is, however, a common feature of both the non-Supported and Supported catalysts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Bas Janssens - One of the best experts on this subject based on the ideXlab platform.
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universal central extension of the lie algebra of hamiltonian vector fields
International Mathematics Research Notices, 2016Co-Authors: Bas Janssens, Cornelia VizmanAbstract:For a connected symplectic manifold X, we determine the universal central extension of the Lie algebra ham(X) of hamiltonian vector fields. We classify the central extensions of ham(X), of the Lie algebra sp(X) of symplectic vector fields, of the Poisson Lie algebra C 1 (X), and of its compactly Supported Version C 1 c (X).
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universal central extension of the lie algebra of hamiltonian vector fields
arXiv: Symplectic Geometry, 2015Co-Authors: Bas Janssens, Cornelia VizmanAbstract:We determine the universal central extension of the Lie algebra of hamiltonian vector fields, thereby classifying its central extensions. Furthermore, we classify the central extensions of the Lie algebra of symplectic vector fields, of the Poisson Lie algebra, and of its compactly Supported Version.
Andreas Schüler - One of the best experts on this subject based on the ideXlab platform.
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Ni 3 N as an Active Hydrogen Oxidation Reaction Catalyst in Alkaline Medium
Angewandte Chemie (International ed. in English), 2019Co-Authors: Anna Krammer, Chia-shuo Hsu, Hao Ming Chen, Andreas SchülerAbstract:Hydroxide-exchange membrane fuel cells can potentially utilize platinum-group-metal (PGM)-free electrocatalysts, offering cost and scalability advantages over more developed proton-exchange membrane fuel cells. However, there is a lack of non-precious electrocatalysts that are active and stable for the hydrogen oxidation reaction (HOR) relevant to hydroxide-exchange membrane fuel cells. Here we report the discovery and development of Ni3 N as an active and robust HOR catalyst in alkaline medium. A Supported Version of the catalyst, Ni3 N/C, exhibits by far the highest mass activity and break-down potential for a PGM-free catalyst. The catalyst also exhibits Pt-like activity for hydrogen evolution reaction (HER) in alkaline medium. Spectroscopy data reveal a downshift of the Ni d band going from Ni to Ni3 N and interfacial charge transfer from Ni3 N to the carbon support. These properties weaken the binding energy of hydrogen and oxygen species, resulting in remarkable HOR activity and stability.
Tore Hansen - One of the best experts on this subject based on the ideXlab platform.
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a general approach for preparation of polymer Supported chiral organocatalysts via acrylic copolymerization
Journal of Organic Chemistry, 2010Co-Authors: Tor E Kristensen, Kristian Vestli, Martin Gjerde Jakobsen, Finn K Hansen, Tore HansenAbstract:Polymer-Supported chiral organocatalysts, as well as most other forms of immobilized catalysts, are traditionally prepared by a postmodification approach where modified catalyst precursors are anchored onto prefabricated polymer beads. Herein, we report an alternative and more scalable approach where polymer-Supported chiral enamine and iminium organocatalysts are prepared in a bottom-up fashion where methacrylic functional monomers are prepared in an entirely nonchromatographic manner and subsequently copolymerized with suitable comonomers to give cross-linked polymer beads. All syntheses have been conducted on multigram scale for all intermediates and finished polymer products, and the catalysts have proven successful in reactions taking place in solvents spanning a wide range of solvent polarity. While polymer-Supported proline and prolineamides generally demonstrated excellent results and recycling robustness in asymmetric aldol reactions of ketones and benzaldehydes, the simplest type of Jorgensen/Hayashi diarylprolinol TMS-ether showed excellent selectivity, but rather sluggish reactivity in the Enders-type asymmetric cascade. The polymer-Supported Version of the first-generation MacMillan imidazolidinone had a pattern of reactivity very similar to that of the monomeric catalyst, but is too unstable to allow recycling.