Synthesis of 2-azidoethyl α-d-mannopyranoside orthogonally protected and selective deprotections

4 páginas, 1 figura, 2 esquemas.We present the synthesis of a fully orthogonally protected mannosyl glycoside 1 and the corresponding methods for selective deprotections. Mannosyl glycoside 1 contains a functionalized linker at the anomeric position to allow for the attachment of carbohydrate units to scaffolds in order to prepare carbohydrate multivalent systems.We would like to thank FIS (PI030093), for financial supportPeer reviewe

Measurement of hadron and lepton-pair production at 161 GeV<root s<172 GeV at LEP

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Searches for scalar top and scalar bottom quarks in e(+)e(-) interactions at 161GeV &lt;=root s &lt;= 183GeV

Searches for scalar top and scalar bottom quarks have been performed at center-of-mass energies between 161 GeV and 183 GeV using the L3 detector at LEP. No signal is observed. Model-independent limits on production cross sections are determined for the two decay channels t̃1 → cχ̃0 1 and b̃1 → b χ̃0 1. Within the framework of the Minimal Supersymmetric extension of the Standard Model mass limits are derived. For mass differences between t̃1 and χ̃0 1 greater than 10 GeV a 95% C.L. limit of 81.5 GeV is set on the mass of the Supersymmetric partner of the left-handed top. A supersymmetric partner of the left-handed bottom with a mass below 80 GeV is excluded at 95% C.L. if the mass difference between b̃1 and χ̃1 is greater than 20 GeV. © 1999 Published by Elsevier Science B.V. All rights reserved

Measurement of the inclusive charmless semileptonic branching fraction of beauty hadrons and a determination of vertical bar V-ub vertical bar at LEP RID C-4549-2008 RID C-5719-2008

A measurement of the inclusive charmless semileptonic branching fraction of beauty hadrons, b --&gt; X-u l nu, has been performed using almost two million hadronic Z decays collected by the L3 experiment at LEP, yielding the result: Br(b --&gt; X-u l nu) = (3.3 +/- 1.0 +/- 1.7) x 10(-3). The first uncertainty is statistical and the second is systematic. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element V-ub extracted from this measurement is: V-ub = (6.0(-1.0-1.9)(+0.8+1.4) +/- 0.2) x 10(-3), where the uncertainties are statistical, systematic and theoretical, respectively. (C) 1998 Elsevier Science B.V. All rights reserved

The Q(2) evolution of the hadronic photon structure function F-2(gamma) at LEP RID C-2983-2009 RID C-4549-2008 RID C-5719-2008

New measurements at a centre-of-mass energy root s similar or equal to 183 GeV of the hadronic photon structure function F-2(gamma)(x) in the Q(2) interval, 9 GeV2 less than or equal to Q(2) less than or equal to 30 GeV2, are presented. The data, collected in 1997 with the L3 detector, correspond to an integrated luminosity of 51.9 pb(-1). Combining with the data taken at a centre-of-mass energy of 91 GeV, the evolution of F-2(gamma) With Q(2) is measured in the Q(2) range from 1.2 GeV2 to 30 GeV2. F-2(gamma) shows a linear growth with ln Q(2); the value of the slope alpha(-1)d F-2(gamma)(Q(2))/dlnQ(2) is measured in two x bins from 0.01 to 0.2 and is somewhat higher than predicted. (C) 1999 Published by Elsevier Science B.V. All rights reserved