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The impact of spilled explosives, their by-products and degradation products on human beings and the environment has been
recognised as a serious problem at areas of existing and former ammunition plants. In nature, aerobic and anaerobic degradation
processes of explosives and their accompanying compounds yield polar contaminants with relatively high water solubilities.
Most are potentially carcinogenic and mutagenic. An HPLC method applying UV-detection for nitroaromatic compounds and amperometric
detection for aminoaromatic and phenolic compounds was used for monitoring the degradation of explosives in a polluted groundwater
sample under natural conditions. Analysis was performed by direct injection of aliquots of the sample after exposition to
daylight for different periods of time.
Received: 6 January 1996/Revised: 7 March 1996/Accepted: 13 March 1996 相似文献
4.
Stefan Müllegger Kathrin H?nel Thomas Strunskus Christof W?ll Adolf Winkler 《Chemphyschem》2006,7(12):2552-2558
Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been applied to reveal the molecular arrangement of ultrathin oligophenyl films [p-quaterphenyl (4P) and p-hexaphenyl (6P)] on Au(111). In the half-monolayer films the molecules lie flat on the surface but still have a considerable inter-ring twist of 30 degrees -40 degrees , similar to the gas-phase conformation. In the saturated monolayer film the second half of the molecules is side-tilted by an angle of less than 66 degrees with respect to the surface. This arrangement is already similar to that in bulk net planes of thicker films parallel to the surface, that is, the 4P(211) and 6P(21-3) planes, respectively. 相似文献
5.
Threshold energies Et are determined for photoelectron emission by 20 inorganic anions in aqueous solution (7.1 < Et < 9.1 eV). Calculated values of Et for Cl?, Br?, I? agree with experiment. The Et are correlated with charge-transf absorption spectra. 相似文献
6.
Michielin O Zoete V Gierasch TM Eckstein J Napper A Verdine G Karplus M 《Journal of the American Chemical Society》2002,124(37):11131-11141
A conformational analysis of a stereochemically complete set of peptide analogues based on a cis-enediol unit is presented. The cis-enediol unit, which can replace a two or a three amino acid segment of a peptide, contains two "side chains", four asymmetrical carbon atoms, and six free dihedral angles. To determine the accessible conformational space, the molecules are divided into three fragments, each containing two free dihedral angles. The energy surfaces are computed for all dihedral angle values, and the possible conformations of the cis-enediol unit analogues are built using all combinations of the surface minima. Such a "build-up" procedure, which is very fast, is able to reproduce 75% of the minima obtained from a full dihedral angle exploration of the conformational space. The cis-enediol unit minima are compared with the corresponding di- and tripeptide minima; all peptide minima can be closely matched by a cis-enediol unit minimum of low energy (less than 2.2 kcal/mol above the lowest energy conformer). However, there are low energy minima of the cis-enediol unit that have no corresponding minima in peptides. The results are shown to depend strongly on the chirality of the analogues. The ability of each of the stereoisomers to mimic natural peptides, evaluated by the present approach, is correlated with its experimental activity in a renin inhibition assay. 相似文献
7.
The impact of spilled explosives, their by-products and degradation products on human beings and the environment has been
recognised as a serious problem at areas of existing and former ammunition plants. In nature, aerobic and anaerobic degradation
processes of explosives and their accompanying compounds yield polar contaminants with relatively high water solubilities.
Most are potentially carcinogenic and mutagenic. An HPLC method applying UV-detection for nitroaromatic compounds and amperometric
detection for aminoaromatic and phenolic compounds was used for monitoring the degradation of explosives in a polluted groundwater
sample under natural conditions. Analysis was performed by direct injection of aliquots of the sample after exposition to
daylight for different periods of time.
Presented as a poster at the Anakon ’95 Conference in Schliersee, April 24–26, 1995 相似文献
8.
Fritz Eckstein 《Angewandte Chemie (International ed. in English)》1983,22(6):423-439
Nucleoside phosphorothioates are analogues of nucleotides with a wide range of applications. Thus, on the one hand, in many but not all cases they are more stable against hydrolysis than the unmodified nucleotides—a property which they share with other nucleotide analogues. On the other hand, however, they are good substrates for many, but not all reactions where the nucleotide or the phosphorothioate group is transferred to an acceptor other than H2O. As a consequence, once incorporated into a system such as DNA, phosphorothioates cannot be easily removed. What makes these compounds unique to a certain extent is the chirality at the phosphorus center if two nonequivalent residues are linked to the phosphorothioate group. This opens the way for the use of these compounds to investigate stereochemical aspects of enzymatic reactions. In addition to these properties, there are those expected from exchange of an oxygen for a sulfur atom in a phosphate group, e.g. the increased affinity towards mercury derivatives and the large chemical shift of the 31P-NMR sinals. If one considers how many biologically interesting compounds contain phosphate groups, the considerable interest in these nucleotide analogues is not surprising. 相似文献
9.
Y. Eckstein D. P. Lee R. P. Quirk P. Dreyfuss 《Journal of polymer science. Part A, Polymer chemistry》1980,18(6):2021-2031
Methods for the determination of the number of the number of polytetrahydrofuran branches in neoprene-g-polytetrahydrofuran were examined. Only two suitable methods were found; namely, termination of oxonium ions by triphenylphosphine followed by 31P-NMR and termination with NH4OH? NH4Cl buffer and reaction with fluorescamine followed by fluorescence spectroscopy. Both methods led to the conclusion that Neoprene W has 9 ± 1 active halogens per mole that can be used to initiate tetrahydrofuran polymerization when silver salts are added. Among the methods examined in this study the fluorescence method was the most reliable, most reproducible, fastest, and simplest. 相似文献
10.