Coupling of inverse gas chromatography at infinite dilution (IGC-ID) with a controlled modification of a solid surface

This paper presents a new method for studying the surface of a heterogeneous solid by inverse gas chromatography at infinite dilution (IGC-ID). After saturating the high-energy sites by impregnation with a suitable polymer, the chromatographic probes visit the low energy sites, which are not visible by conventional IGC-ID. This method has been used to study the two types of surface of talc: lateral and basal surfaces. In the second part of the paper the influence of the structure of the polymer on the impregnation is examined. In particular it is shown that a polymer with a linear structure is more able to fit a rough surface than is a branched or a cyclic polymer.     

Étude des restes pour les suites de Van Der Corput généralisées

We get the asymptotic behaviour of the remainder function with respect to the Van Der Corput generalized sequences construted in a previous paper (in Bulletin de la S.M.F, n^o 109, 1981). As a consequence, we obtain the intervals [0, a] for which the remainder is bounded. Moreover, we give an explicit formula for the remainder with respect to the Van Der Corput sequence in the r-adic system.     

Clinical investigations of catecholaminergic systems using liquid chromatography with electrochemical detection

Catecholamine levels in body fluids are reliable biochemical markers of several types of tumors, cardiovascular diseases and hereditary and metabolic disorders. Reversed-phase liquid chromatography with electrochemical detection (RPLC-EC) is now the method of choice for catecholamine analysis.     

Optimization of a binary transcoding single filter used for character recognition

We propose a new type of optical filter for character recognition. We intend to show that a unique optimized filter is suitable for binary transcoding of an alphabetical set. The unique filtering consists of a multiplexing from a superposition of holographic filters. Synthesis can be implemented either by analog holography or by numerical holography. A verification obtained from a limited alphabet is presented.     

A stable distannirane

The first three-membered ring compound containing two tin and one carbon atoms, 1,1,2,2-tetra(2,4,6-triisopropylphenyl)-3-fluorenylidene-1,2-distannirane, has been synthesized in a two-step procedure from the 9-[bis(2,4,6-triisopropylphenyl)fluorostannyl]chloromethylenefluorene.     

Asymmetric Catalysis. Part 149 [1]. Synthesis of New Chiral Tridentate Ligands for Enantioselective Catalysis

Summary. The synthesis of new chiral tridentate ligands is reported which coordinate transition metals in a meridional way. The ligands contain a pyridine ring, an oxazoline ring, and a strongly coordinating diphenylphosphanyl group. The methionine-derived ligand forms a copper complex, which has been studied by X-ray crystallography. The new ligands were tested in models of enantioselective catalyses, such as hydrogenation of ketopantolactone, hydrosilylation of acetophenone, and transfer hydrogenation of acetophenone.X-ray structure analysesReceived March 4, 2003; accepted March 4, 2003 Published online August 18, 2003     

The mass spectra of carboxylic acids—I: Fragmentation mechanisms in maleic and fumaric acids and related compounds

The mass spectra of maleic acid, maleic acid-2,3-d, fumaric acid and fumaric acid-2,3-d have been examined and fragmentation mechanisms are proposed for these compounds. The molecular ion of the cis-acid fragments via H atom transfer from one carboxyl group to the other followed by loss of CO₂. The trans acid does not fragment significantly by this route and the former effect may be characteristic of molecules containing two carboxyl groups cis-oriented to each other. This hypothesis was successfully tested by examining the mass spectra of citraconic, itaconic and phthalic acids. Itaconic and mesaconic acids show some of the fragmentation characteristics of fumaric acid.