Activity of national engineering-geological societies and groups

Sans résumé

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Activity of national engineering-geological societies and groups

     

Direct analysis of silica gel extracts from immunostained glycosphingolipids by nanoelectrospray ionization quadrupole time-of-flight mass spectrometry

A combined strategy of preparative high-performance thin-layer chromatography overlay assay and mass spectrometry was established for the structural characterization of immunostained glycosphingolipids (GSLs) in silica gel extracts. Crude chloroform/methanol/water (30/60/8, v/v/v) extracts of immunostained TLC bands were analyzed by nanoelectrospray low-energy CID mass spectrometry without further purification. The GSL species investigated were isomeric monosialogangliosides of the neolacto series from a ganglioside preparation of human granulocytes, the disialoganglioside GD3 from a human melanoma lipid extract, and ganglio series Gg3Cer of a neutral GSL preparation from murine lymphoreticular MDAY-D2 cells. For the specific detection of lipid-bound oligosaccharides, polyclonal chicken IgY, murine monoclonal IgG3, and IgM antibodies were used. The resulting mass spectra show that only analytical quantities of approximately 1 microg of a single GSL within a complex mixture are required for the structure determination of immunostained GSLs by MS and MS/MS. All species investigated were detected as singly charged deprotonated molecular ions, and neither buffer-derived salt adducts nor coextracted contaminants from the immunostaining procedure or the silica gel layer were observed. This effective HPTLC-MS-joined procedure offers a wide range of applications for any carbohydrate binding agents such as bacterial toxins, plant lectins, and others.     

A kinetic model of aqueous-phase alkali hydrolysis of 2,4,6-trinitrotoluene

Alkali hydrolysis of 2,4,6-trinitrotoluene (TNT) was studied using batch experiments with starting pH values 11 and 12 in glass conical flasks covered with aluminum foil. Isothermal (25 and 40 degrees C) as well as non-isothermal experiments were conducted. Experiments starting at pH 12 resulted in >95% reduction in the concentration of TNT; those starting at pH 11 had a maximum reduction of 20-25% in TNT concentration. In all the experiments, one major stable intermediate was produced but it could not be identified. The experimental data were used to determine the overall stoichiometry of TNT and hydroxyl ions. Approximately 100 M (standard deviation 11.4) of hydroxyl ions were consistently consumed per mole of TNT. However, control experiments showed that all but 13 M (standard deviation 2) of hydroxyl ions were consumed in reactions not related to TNT. A simple kinetic model involving formation of the intermediate was proposed to account for changes in concentrations of TNT and hydroxyl ions. The rate constants and activation energies of the reactions were identified using isothermal data and the kinetic model was then used to predict the experimental data in the non-isothermal experiments reasonably well.     

Enhancement of nonlinear effects using photonic crystals

The quest for all-optical signal processing is generally deemed to be impractical because optical nonlinearities are usually weak. The emerging field of nonlinear photonic crystals seems destined to change this view dramatically. Theoretical considerations show that all-optical devices using photonic crystal designs promise to be smaller than the wavelength of light, and to operate with bandwidths that are very difficult to achieve electronically. When created in commonly used materials, these devices could operate at powers of only a few milliwatts. Moreover, if these designs are combined with materials and systems that support electromagnetically induced transparency, operation at single-photon power levels could be feasible.