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The Factorization Method, a well established method in inverse scattering problems for bounded obstacles, is extended to the case of scattering by a periodic surface. The method is rigorously proved to provide accurate reconstructions for the cases of the total field satisfying a Dirichlet or an impedance boundary condition on the scattering surface. A(More)
This paper explores the role of association on the adsorption isotherms of beta-lactoglobulin A on a weakly hydrophobic stationary phase at 4 degrees C and mobile phases of 0.85 M and 1 M ammonium sulfate, pH 4.5. The isotherms, obtained by frontal analysis, show an S-shape and the corresponding Scatchard plots indicate positive cooperativity. The slopes(More)
Cellulose and cellulose derivatives are biopolymers which are often used as stationary phases for the separation of enantiomers. Describing the mechanism of such separations is a difficult task due to the complexity of these phases. In the present study, we attempt to elucidate the types of interactions occurring between a diol intermediate for a LTD(4)(More)
A search was implemented for a microbial lipase capable of bioconverting a diester (dimethyl 5-(3-(2-(7-chloroquinolin-2-yl)ethyl)phenyl)4,6-dithianon to its S-ester acid, an intermediate in the production of Verlukast (a leukotriene receptor antagonist). Required properties of the sought-after enzyme included a high enantiomeric selectivity (e.e. >98%),(More)
An efficient asymmetric synthesis of 11-β-HSD inhibitor 1 has been accomplished in five linear steps and 53% overall yield, starting from the readily available 3-chloro-1-phenylpropan-1-one. The key feature of the synthesis includes an asymmetric methallylation of 3-chloro-1-phenylpropan-1-one catalyzed by the highly effective organocatalyst(More)
[reaction: see text] Diisobutylaluminum hydride (DIBAL-H) and triisobutylaluminum have been found to be outstanding reductants for secondary phosphine oxides (SPOs). All classes of SPOs can be readily reduced, including diaryl, arylalkyl, and dialkyl members. Many SPOs can now be reduced at cryogenic temperatures, and conditions for preservation of(More)
Using reversed-phase high-performance thin-layer chromatography and a methanol-water mixture as the mobile phase, the lipophilicity of 12 new synthesized derivatives is studied. The first eight compounds have as a basic chemical structure aryliden-hydrazino-selenazoles, and the second group of the three compounds belongs to aroyl-hydrazinoselenazoles. The(More)
LCMS incorporating a quadrupole time of flight mass spectrometer was used to identify impurities found in a chemical process development sample of a novel integrase inhibitor, raltegravir. The combination of accurate mass measurement in full scan mode followed by construction of targeted masses for further MSMS interrogation allowed for the determination of(More)
An enantioselective copper-catalyzed asymmetric conjugate addition of Me2Zn to (Z)-nitroalkenes led to the formation of all-carbon quaternary stereogenic centers with high stereoselectivity. The key features of the new method are the unprecedented use of [(MeCN)4Cu]PF6 in conjunction with the Hoveyda ligand L1 and the use of (Z)-nitroalkene substrates so(More)
A practical noncryogenic process for the Aggarwal stereospecific boronate rearrangement with chiral secondary benzylic carbamates has been developed. The use of LDA instead of sec-BuLi combined with an in situ trapping of the unstable lithiated carbamate was critical to success. Furthermore, this new process increased the substrate scope to include the(More)