| 1. |
- Aplander, Karolina, et al.
(author)
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Asymmetric Lewis Acid Catalysis in Water: alpha-Amino Acids as Effective Ligands in Aqueous Biphasic Catalytic Michael Additions
- 2009
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In: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; :6, s. 810-821
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Journal article (peer-reviewed)abstract
- This article explores the potential of native a-amino acids as chiral ligands in aqueous asymmetric Lewis acid catalysis, employing the C-C bond forming Michael addition as a model reaction. Some insights are provided regarding the details of Yb(OTf)(3)/alpha-amino acid-catalyzed Michael additions in water through new kinetic data as well as studies on how both yield and selectivity are influenced by variations in metal/ligand ratio, pH, temperature, and structure of the a-amino acid, Through this investigation it was found that reaction conditions that require only 5 mol-% of the Lewis acid, provides enantiomeric excesses of up to 79 % and is applicable to a wider range of donors and acceptors than previously demonstrated. Importantly, it was also demonstrated that the a-amino acid complexed ytterbium. catalyst might have potential for large-scale applications as it displays not only large ligand accelerations, but also good solubility and stability in water. It can be recycled multiple times without appreciable loss of activity. The result is a promising example of a water-compatible chiral Lewis acid. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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| 2. |
- Bruzzi, M, et al.
(author)
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Radiation-hard semiconductor detectors for SuperLHC
- 2005
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In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 541:1-2, s. 189-201
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Journal article (peer-reviewed)abstract
- An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016cm-2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.
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