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51.
The solid-phase synthesis of branched lacto-N-neohexaose derivative 1 occurring in human milk is described. The new building block of lactose 3 bearing the orthogonal temporary hydroxy protecting groups 9-fluorenylmethyloxycarbonyl (Fmoc) and levulinoyl (Lev) has been prepared. Its use, together with that of lactosamine donor 4, glucosamine donor 5, and O-galactosyl trichloroacetimidate 6, has enabled the preparation of hexasaccharide 22 following two different approaches in excellent overall yield (43%, 90% per step over eight steps). An additional key feature of this work is the successful use of newly prepared ester-type linker 2, having a benzylic spacer connected to the anomeric oxygen. This linker presents the advantage of producing a benzylic anomeric moiety after cleavage from the polymer support, which could be easily removed to obtain the unprotected oligosaccharide 1. 相似文献
52.
M. Bernas M. Langevin G. Parrot F. Pougheon E. Quiniou P. Roussel Ph. Dessagne W. -D. Schmidt-Ott 《Zeitschrift für Physik A Hadrons and Nuclei》1985,321(3):435-438
The mass excess of the147Gd nucleus was measured from the144Sm(12C,9Be)147Gd reaction using the 72 MeV12C beam of the Orsay MP Tandem and the “Bacchus” magnetic spectrometer. The measurement is auto-calibrated by the10Be spectrum from the144Sm(12C,10Be) reaction. The derived value of the mass excess of147Gd is ?75.401±0.025 MeV. It is compared with other recent results and with calculated values. 相似文献
53.
Hachemi Belghith Casimir Blonski Alain Klab Jacques Pri Jean Roussel 《Journal of mass spectrometry : JMS》1989,24(9):718-722
Analysis by electron impact and metastable ions (MIKE technique) of the fragmentation patterns for one acyclic and two cyclic N-phosphorylated ureas reveals for the first case an isomerization from nitrogen to the ureido oxygen atom of the phosphoryl group and subsequent fragmentation. For the other two cases, fragments result from P? N bond breaking and ring-opening. Possible involvement in the biotin-ATP activation process is discussed. 相似文献
54.
What is new in the field of neutrino detection? In addition to new projects probing both the low and high ends of the neutrino energy scale, an inexpensive, effective technique is being developed to allow tagging of antineutrinos in water Cherenkov (WC) detectors via the addition to water of a solute with a large neutron cross-section and energetic γ daughters. Gadolinium is an excellent candidate since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially available gadolinium trichloride. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields an 8.0 MeV gamma cascade easily seen in detectors like Super-Kamiokande. The uses of GdCl3 as a possible upgrade for the Super-Kamiokande detector — with a view toward improving its performance as an antineutrino detector for supernova neutrinos and reactor neutrinos — are discussed, as are the ongoing R&;D efforts which aim to make this dream a reality within the next two years. 相似文献
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Different O-glycosyl trichloroacetimidates bearing base sensitive Fmoc protected hydroxy groups were efficiently prepared with CCl(3)CN using a catalytic amount of sodium hydride. The resulting glycosyl donors were engaged in glycosylation reactions both in solution and on solid support with a new ester-type linker with good results. In both approaches, Fmoc groups were afterward quantitatively cleaved using mild basic conditions. 相似文献
58.
Fabien Roussel Mauricette Hilly Françoise Chrétien Jean-Pierre Mauger Yves Chapleur 《Journal of carbohydrate chemistry》2013,32(6):697-707
ABSTRACT (2-Hydroxyethyl) 2-deoxy-α-D-threo-pentopyranoside 3,4,2′-trisphosphate (3) has been prepared starting from allyl-α-D-xylopyranoside. The suitably protected 2-deoxy intermediate obtained by judicious selective protection and deprotection has been phosphorylated using the phosphoramidite methodology. Final deprotection gave the expected analogue of myo-inositol 1,4,5-trisphosphate. 相似文献
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An adaptive mulitresolution method based on a second-order finite volume discretization is presented for solving the three-dimensional compressible Navier–Stokes equations in Cartesian geometry. The explicit time discretization is of second-order and for flux evaluation a 2–4 Mac Cormack scheme is used. Coherent Vortex Simulations (CVS) are performed by decomposing the flow variables into coherent and incoherent contributions. The coherent part is computed deterministically on a locally refined grid using the adaptive multiresolution method while the influence of the incoherent part is neglected to model turbulent dissipation. The computational efficiency of this approach in terms of memory and CPU time compression is illustrated for turbulent mixing layers in the weakly compressible regime and for Reynolds numbers based on the mixing layer thickness between 50 and 200. Comparisons with direct numerical simulations allow to assess the precision and efficiency of CVS. 相似文献