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1.
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
2.
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
3.
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
4.
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
5.
Kathrin Wichmann Bianca Antonioli Tilo Shnel Marco Wenzel Kerstin Gloe Karsten Gloe Jason R. Price Leonard F. Lindoy Alexander J. Blake Martin Schrder 《Coordination chemistry reviews》2006,250(23-24):2987
In the discussion that follows some of the more recent progress in the area of anion binding by synthetic polyamine receptors is presented, with emphasis given to work undertaken by the authors’ groups. A continuing theme in these studies has been the relationship between receptor structure and its anion extraction properties.Systematic solvent extraction and structural studies for halide and perrhenate complexes with polyamines of tripodal, macrocyclic and macrobicyclic architecture that contain both aromatic moieties and four to eight amine functions have been performed in order to derive relevant structure-binding/extractability relationships. The results demonstrate that the binding and extraction behaviour of the polyamines towards halides and perrhenate is a complex function of their structural features, degree of protonation and lipophilic properties. The extraction is characterized by the preferred formation of mono- and diprotonated amine species in the organic phase. X-ray structure studies of iodide and perrhenate complexes with open-chain tetraamino derivatives and octaamino cryptands in different protonation states lead to the conclusion that in the first case only limited chelation of the anion occurs and in the second only highly protonated species are able to encapsulate the anion. The structural patterns observed are strongly influenced by the presence of water molecules in the crystals. 相似文献
6.
Jimmy Maillard Kathrin Klehs Christopher Rumble Eric Vauthey Mike Heilemann Alexandre Fürstenberg 《Chemical science》2021,12(4):1352
Although biological imaging is mostly performed in aqueous media, it is hardly ever considered that water acts as a classic fluorescence quencher for organic fluorophores. By investigating the fluorescence properties of 42 common organic fluorophores recommended for biological labelling, we demonstrate that H2O reduces their fluorescence quantum yield and lifetime by up to threefold and uncover the underlying fluorescence quenching mechanism. We show that the quenching efficiency is significantly larger for red-emitting probes and follows an energy gap law. The fluorescence quenching finds its origin in high-energy vibrations of the solvent (OH groups), as methanol and other linear alcohols are also found to quench the emission, whereas it is restored in deuterated solvents. Our observations are consistent with a mechanism by which the electronic excitation of the fluorophore is resonantly transferred to overtones and combination transitions of high-frequency vibrational stretching modes of the solvent through space and not through hydrogen bonds. Insight into this solvent-assisted quenching mechanism opens the door to the rational design of brighter fluorescent probes by offering a justification for protecting organic fluorophores from the solvent via encapsulation.Overtones and combinations of O–H vibrations in the solvent efficiently quench red-emitting fluorophores by resonant energy transfer. 相似文献
7.
Richard Behnke Franka Stahl Kathrin Duske Mareike Warkentin Margit Schwartz Burkhard Hinz Udo Walther 《Molecules (Basel, Switzerland)》2022,27(12)
Depending on their composition, plastics have a cytotoxic potential that needs to be evaluated before they are used in dentistry, e.g., as orthodontic removable appliances. Relevant guidelines set out requirements that a potential new resin in the medical field must meet, with a wide scope for experimental design. In the present study, test specimens of different geometries consisting of varying polymers (Orthocryl®, Orthocryl® LC, Loctite® EA 9483, Polypropylene) were soaked for different periods of time, then transferred to cell culture medium for 24 h, which was subsequently used for 24-h cultivation of A549 cells, followed by cytotoxicity assays (WST-1, Annexin V-FITC-propidium iodide (PI) flow cytometry). In this context, a reduction in the cytotoxic effect of the eluates of test specimens prepared from Orthocryl® LC and Loctite® EA 9483 was particularly evident in the Annexin V-FITC-PI assay when the soaking time was extended to 48 h and 168 h, respectively. Consistent with this, a reduced release of potentially toxic monomers into the cell culture medium, as measured by gas chromatography-mass spectrometry, was observed when the prior soaking time of test specimens of all geometries was extended. Remarkably, a significant increase in cytotoxic effect was observed in the WST-1 assay, which was accompanied by a higher release of monomers when the thickness of the test sample was increased from 0.5 to 1.0 mm, although an elution volume adapted to the surface area was used. However, further increasing the thickness to 3.0 mm did not lead to an increase in the observed cytotoxicity or monomer release. Test specimens made of polypropylene showed no toxicity under all test specimen sizes and soaking time conditions. Overall, it is recommended to perform toxicity studies of test specimens using different geometries and soaking times. Thereby, the influence of the different specimen thicknesses should also be considered. Finally, an extension of the test protocols proposed in ISO 10993-5:2009 should be considered, e.g., by flow cytometry or monomer analysis as well as fixed soaking times. 相似文献
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