Chiral molecules possess enantiomers that have non-superimposable chemical structures but exhibit identical nuclear magnetic resonance (NMR) spectra. This feature prevents the use of NMR spectroscopic methods for determination enantiomeric excesses (ee) chiral molecules, using simple mixtures their enantiomers. Recently, however, it was reported addition a symmetrical prochiral molecule (a repo...

The structural motif of α,α-difluoro-substituted carboxyl and carbonyl groups with hydroxy- or amino-substituents at the stereogenic carbon in β-position is found frequently drugs biologically active compounds. A straightforward method for obtaining those targets high enantiomeric purity given by asymmetric difluoro-Reformatsky imino-difluoro-Reformatsky reactions that lead to α,α-difluorinated...

A hexafullereno-diporphyrinoid was obtained in a sequence of cycloaddition steps using porphyrins programmed for [4+2]-cycloaddition reactions and C(60)-fullerene.

carbon nanotubes (cnts) are specific structures with valuable characteristics. in general, the structure of each nanotube is defined by a unique chiral vector. in this paper, different structures of short single-walled cnts are simulated and their mechanical properties are determined using finite element method. for this aim, a simple algorithm is presented which is able to model the geometry o...

The standard view of English reduced auxiliaries takes them to be (postlexical) clitics (Kaisse 1983). However, Spencer (1991) puts forward some persuasive arguments that a subset of these forms, the non-syllabic reduced auxiliaries, are actually aaxes (tense innec-tions) rather than clitics, while the syllabic reduced auxiliaries are post-lexical clitics. We accept the logic of Spencer's posit...

1. INTRODUCTION. This paper discusses whether there are elements in colloquial Sinhala that can be appropriately labeled AUXILIARY verbs, and what evidence there is to motivate such a label. While auxiliaries are thought of as a nearly universal lexical category (Steele 1978), the term is not mentioned in standard works on Sinhala (Gair & Paolillo 1997, Gair 1998), which warrants a closer exami...

One of the problems encountered in CE separations of basic compounds is the adsorption of analytes onto the negatively charged capillary wall which could lead to poor repeatability of migration time and peak area. Additionally, separation of enantiomers of chiral of basic drugs is commonly carried out in low pH buffer which contributes to strong ionic interaction of the cationic drug ions with ...