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  • Analytical Chemistry and Spectroscopy  (3)
  • Crystal structure  (2)
  • sediment  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Redox processes in recent sediments of the river Meuse, The Netherlands (2000)
    Springer
    Biogeochemistry 48 (2000), S. 217-235 
    Details
    ISSN: 1573-515X
    Keywords: diagenesis ; modelling ; organic matter ; pore water ; redox ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO3 in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006268325889
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Mobilisation of Heavy Metals in Contaminated Sediments in the River Meuse, The Netherlands (1999)
    Springer
    Water, air & soil pollution 116 (1999), S. 567-586 
    Details
    ISSN: 1573-2932
    Keywords: Complexation ; diffusion ; heavymetals ; mobilisation ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Due to seasonal variation in bottom-water temperature and degradation of organic matter, the depths of the redox boundaries fluctuate in sediments of the river Meuse. This is reflected by a non-steady state behaviour of heavy metals in the surface sediments. Levels of acid-volatile sulphides suggest that dissolved concentrations of heavy metals in the anoxic pore waters are determined by their respective sulphide phases. However, complexation with dissolved organic ligands may significantly increase dissolved concentrations of heavy metals. In most sediments studied, a distinct peak in dissolved concentrations of heavy metals is measured immediately below the sediment-water interface. This concentration peak may be attributed to degradation of organic matter and oxidation of sulphides. Dissolved concentration gradients indicate that upward diffusion of heavy metals from the sediment can contribute to concentrations in the surface water, although significant effects may be confined to specific locations. In addition, it is shown that release of heavy metals as dissolved species to the surface water is negligible compared to particulate-bound fluxes of heavy metals to the sediment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005146927718
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A new surface roughening method for glass capillary columns. Sodium chloride deposition from suspension (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 447-455 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface roughening by direct deposition of suspension particles ; NaCl used ; High reproducibility when coated with polar phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for roughening the surface of glass capillary columns for subsequent coating with polar stationary phases. A suspension of sodium chloride, obtained by addition of a saturated solution of sodium chloride in methanol to 1,1,1-trichloroethane, is passed through the column at velocities of 1-5 cm/s. During passage of the suspension, particles of sodium chloride deposit spontaneously on the column wall. The amount of sodium chloride deposited on the column wall is a function of the volume of the suspension passed through and of the contact time of the suspension and the column wall. Ultimately the amount of sodium chloride per unit surface area approaches a maximum. Columns covered with this maximum amount of sodium chloride were prepared with high reproducibility and coated with a number of polar stationary phases. Various factors that influence the stability of the suspension and the deposition of sodium chloride are discussed and minimum requirements are given. A theoretical model is proposed for the mechanism of deposition of sodium chloride particles on the glass wall.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020715
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  • 4
    Electronic Resource
    Electronic Resource
    A Unique Copper-Controlled Template Synthesis of Tetradentate N4-Donor Ligands and Their Propeller-Type Linear Trinuclear CuII Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 547-549 
    Details
    ISSN: 1434-1948
    Keywords: Copper ; Trinuclear ; Formamidines ; Magnetism ; Crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In situ reaction of CuII triflate with aminopyridine or aminopyrimidine and triethylorthoformate in ethanol results in unique linear trinuclear CuII complexes with the general formula [Cu3(L-)4](CF3SO3)2(EtOH)x (L = dehydronated ligand N,N′-bis(pyridine-2-yl)formamidine or the new ligand N,N′-bis(pyrimidine-2-yl)formamidine). The structure [Cu-Cu-Cu angle 175.19(2)°] consists of four nearly flat molecules of the ligand which contribute to the propeller-type structure around the Cu-Cu-Cu axis. A strong antiferromagnetic interaction between the CuII ions is observed, resulting in an S = 1/2 ground state below 100 K.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    An Unprecedented, Copper-Mediated, In-Situ Multi-Step Ligand Formation - Synthesis, Structure, and Magnetism of Bis(μ-methoxo)bis[nitrato(2-methoxy- methylamino-3-methylpyridine)copper(II)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1577-1579 
    Details
    ISSN: 1434-1948
    Keywords: Copper ; Methoxo-bridged complexes ; Crystal structure ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel chelating ligand, synthesized in situ within the coordination sphere of CuII from 2-amino-3-methylpyridine, MeOH, and dioxygen from the air, is found to form a strongly coupled, dinuclear methoxo-bridged CuII compound with the formula [Cu(L)(CH3O)(NO3)]2 (L = 2-methoxymethylamino-3-methylpyridine). The geometry around the copper atom is square pyramidal and the Cu-Cu distance within the dinuclear unit is 3.011(2) Å with an Cu-O-Cu angle of 103.13(8)°. Synthesis, X-ray crystal structure, and magnetism are reported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    A study of the electron impact-induced fragmentation of 1,6-diaminohexane (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 995-1001 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectrometric behaviour of 1,6-diaminohexane has been studied with the help of deuterium labelling in every position of the molecule. Extensive intramolecular exchange reactions between the hydrogen atoms of the amino groups and those of the hydrocarbon chain are responsible for the apparent complexity of the fragmentation mode.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210110912
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  • 7
    Electronic Resource
    Electronic Resource
    A study of the fragmentation of cyclopentane-1,3-diols and of cyclopentane-1,2,4-triols (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 702-710 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the two cyclopentane-1,3-diol and of the three cyclopentane-1,2,4-triol stereoisomers have been studied. Extensive deuterium labelling allows the detection of complex processes, especially for the elimination of water from the [M - H2OO]+· and [M]+· ions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210100904
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    Paper (German National Licenses)
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