Adaptive Control Based on Retrospective Cost Optimization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83558/1/AIAA-46741-507.pd

Synthesis of peracetylated D-galactopyranosylidene dihalides

Upon treatment with aluminium trichloride in absolute chloroform, beta -D-galactopyranose penta-O-acetate was converted in high yield into tetra-O-acetyl-beta -D-galactopyranosyl chloride. In the presence of N-bromosuccinimide in boiling carbon tetrachloride, homolytic substitution of the anomeric hydrogen atom in this beta -chloride occurred selectively to afford tetra-O-acetyl-1-bromo-beta -D-galactopyranosyl chloride, in admixture with minor amounts of tetra-O-acetyl-D-galactopyranosylidene chloride. Bromine substitution by fluorine took place with a low stereoselectivity in tetra-O-acetyl-1-bromo-beta -D-galactopyranosyl chloride when treated with 1.25 equiv silver fluoride in acetonitrile, whereas tetra-O-acetyl-beta -galactopyranosylidene fluoride could be prepared in 54% yield with 3.3 equiv AgF. The gem-difluoride could be deacetylated quantitatively. Upon treatment with 1,4-diazabicyclo[2.2.2] octane, peracetylated 1-bromo-beta -D-galactopyranosyl chloride underwent 1,2-elimination of hydrogen bromide to afford 2,3,4,6-tetra-0-acetyl-D-lyxo-hex-1-enopyranosyl chloride in 33 % yield. (C) 2001 Academie des sciences / Editions scientifiques et medicales Elsevier SAS

Using distributed magnetometry in navigation of heavy launchers and space vehicles

Recently, a new technique (magneto-inertial navigation, MINAV) has emerged to address the general problem of reconstructing the inertial velocity of a rigid body moving in a magnetically disturbed region. The contribution of this paper is to apply the developed method, in a prospective spirit, to a case of space navigation in view of estimating the performance improvement that could be obtained using state-of-theart magnetometer technology onboard heavy launchers and other space vehicles. The main underlying idea of the approach is to estimate the inertial velocity by readings of the magnetic field at spatially distributed (known) locations on the rigid body. Mathematically, through a chainrule differentiation involving variables commonly appearing in classic inertial navigation, an estimate of this velocity can be obtained. This paper presents the potential of this method in the field of navigation of heavy launchers passing through particular regions of the Earth magnetosphere as considered, e. g., for upcoming Galileo missions. Numerical results based on the specifications of candidate embedded magnetic sensors stress the relevance of the approach. The presented methodology is patent pending and has been partially funded by CNES

Halogen-substituted (C-beta-D-glucopyranosyl)-hydroquinone regioisomers: Synthesis, enzymatic evaluation and their binding to glycogen phosphorylase

Electrophilic halogenation of C-(2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl) 1,4-dimethoxybenzene (1) afforded regioselectively products halogenated at the para position to the D-glucosyl moiety (8, 9) that were deacetylated to 3 (chloride) and 16 (bromide). For preparing meta regioisomers, 1 was efficiently oxidized with CAN to afford C-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl) 1,4-benzoquinone 2 which, in either MeOH or H2O-THF containing few equivalents of AcCl, added hydrochloric acid to produce predominantly meta (with respect to the sugar moiety) chlorinated hydroquinone derivatives 5 and 18, this latter being deacetylated to 4. The deacetylated meta (4, 5) or para (3, 16) halohydroquinones were evaluated as inhibitors of glycogen phosphorylase (GP, a molecular target for inhibition of hepatic glycogenolysis under high glucose concentrations) by kinetics and X-ray crystallography. These compounds are competitive inhibitors of GPb with respect to alpha-D-glucose-1-phosphate. The measured IC50 values (mu M) [169.9 +/- 10.0 (3), 95 (4), 39.8 +/- 0.3 (5) 136.4 +/- 4.9 (16)] showed that the meta halogenated inhibitors (4, 5) are more potent than their para analogs (3, 16). The crystal structures of GPb in complex with these compounds at high resolution (1.97-2.05 angstrom) revealed that the inhibitors are accommodated at the catalytic site and stabilize the T conformation of the enzyme. The differences in their inhibitory potency can be interpreted in terms of variations in the interactions with protein residues of the different substituents on the aromatic part of the inhibitors. (C) 2011 Elsevier Ltd. All rights reserved