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  • Ostwald ripening  (4)
  • 2-(dimethylaminomethyl)ferrocenyl compounds  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Morphological instabilities in pattern formation by precipitation and crystallization processes (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 19-28 
    Details
    ISSN: 0016-7835
    Schlagwort(e): Key words Anastomoses ; Crystal zoning ; Snow bands ; Liesegang rings ; Ostwald ripening ; Self organization ; Siderite ; Supersaturation theory ; Zebra rock
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192056
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Self-organization of recent rhythmic iron–manganese precipitations in underground mines in the Harz mountains (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 29-37 
    Details
    ISSN: 0016-7835
    Schlagwort(e): Key words Banded mineralization ; Harz mountains ; Self-organization ; Iron ; manganese ; ferrihydrite ; birnessite ; Time-series analysis ; Aquatic systems ; Iron bacteria ; Ostwald ripening
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  A recent early diagenetic banded iron–manganese mud has been forming underground in a closed lead–zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192057
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Morphological instabilities in pattern formation by precipitation and crystallization processes (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 19-28 
    Details
    ISSN: 1437-3262
    Schlagwort(e): Anastomoses ; Crystal zoning ; Snow bands ; Liesegang rings ; Ostwald ripening ; Self organization ; Siderite ; Supersaturation theory ; Zebra rock
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192056
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Self-organization of recent rhythmic iron-manganese precipitations in underground mines in the Harz mountains (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 29-37 
    Details
    ISSN: 1437-3262
    Schlagwort(e): Banded mineralization ; Harz mountains ; Self-organization ; Iron, manganese, ferrihydrite, birnessite ; Time-series analysis ; Aquatic systems ; Iron bacteria ; Ostwald ripening
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192057
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. 58. Zur Kenntnis von 2-(Dimethylaminomethyl)ferrocenyl-Verbindungen des Vanadiums, Molybdäns, Wolframs, Thoriums und Urans (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 613 (1992), S. 88-92 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Transition metal alkyl compounds ; vanadium ; molybdenum ; tungsten ; thorium ; uranium ; 2-(dimethylaminomethyl)ferrocenyl compounds ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Contributions to the Chemistry of Transition Metal Alkyl Compounds. 58 On 2-(Dimethylaminomethyl)ferrocenyl Compounds of Vanadium, Molybdenum, Tungsten, Thorium, and UraniumEarlier results according to which dimethylaminomethylferrocenyl groups (FcN) are able to form stable organometallic chelate compounds were confirmed by synthesis of the heterobimetallic chelate compounds (FcN)2VO · Li(acac) II, (FcN)MoO2(acac) III, (FcN)WOCl3 IV, (FcN)Th(acac)3 V, and (FcN)UO2(acac) VI from the corresponding metal acetylacetonates or oxidchlorides and (FcN)Li I. The new compounds were characterized by elemental analysis, the i.r., 1H-n.m.r., and electron spectra and by their effective magnetic moments.
    Notizen: Frühere Befunde, wonach Dimethylaminomethylferrocenyl-Gruppen (FcN) zur Bildung stabiler Organoübergangsmetallchelate befähigt sind, wurden durch die Synthese der heterobimetallischen Chelatkomplexe (FcN)2VO · Li(acac) II, (FcN)MoO2(acac) III, (FcN)WOCl3 IV, (FcN)Th(acac)3 V und (FcN)UO2(acac) VI aus den betreffenden Metalloxidchloriden bzw. -acteylacetonaten und (FcN)Li I bestätigt.  -  Die erhaltenen Verbindungen wurden durch Elementaranalysen, IR-, 1H-NMR- und UV-VIS-Spektren sowie Bestimmung der effektiven magnetischen Momente charakterisiert.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19926130115
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Beiträge zur Lanthanoidchemie. II. Zur Kenntnis von 2-(Dimethylaminomethyl)ferrocenyl-Verbindungen des Yttriums, Dysprosiums und Holmiums (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 618 (1992), S. 163-167 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Organolanthanide chemistry ; yttrium ; dysprosium ; holmium ; 2-(dimethylaminomethyl)ferrocenyl compounds ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Contributions to Organolanthanide Chemistry. II. On 2-(dimethylaminomethyl)ferrocenyl Compounds of Yttrium, Dysprosium, and HolmiumEarly reports about the ability of the 2-(dimethylaminomethy1)ferrocenyl group to form stable heterobimetallic organolanthanide(III) compounds have been confirmed by the synthesis of the organolanthanide(III) derivatives (C5H5)2Ln(FcN) [Ln = Y (II), Dy (III), Ho (IV)], C5H5Dy(FcN)2 · 2,5 THF (V) und C5H5Ln(FcN)Cl [Ln = Dy (VI), Ho (VII)] from the corresponding cyclopentadienyllanthanide(III) chlorides (C5H5)2LnCl or C5H5LnCl2 resp. and (FcN)Li (I). The products have been characterized by elemental analyses, IR-, 1H-NMR, 13C-NMR and UV/Vis spectra as well as mass spectra and the determination of their effective magnetic moments.
    Notizen: Frühere Befunde, wonach 2-(Dimethylaminomethyl)ferrocenyl-Gruppen (FcN) zur Bildung stabiler, heterobimetallischer Organolanthanoid(III)-Verbindungen befähigt sind, wurden durch die Synthese der Organoseltenerd(III)-Derivate (C5H5)2SE(FcN) [SE = Y (II), Dy (III), Ho (IV)], C5H5Dy(FcN)2 · 2,5 THF (V) und C5H5SE(FcN)Cl [SE = Dy (VI), Ho (VII)] aus den betreffenden Cyclopentadienylseltenerd(III)-chloriden (C5H5)2SECl bzw. C5H5SECl2 und (FcN)Li (I) bestätigt. Die erhaltenen Verbindungen wurden durch Elementaranalysen, IR-, 1H-NMR-, 13C-NMR- und UV-Vis-Spektren sowie durch Bestimmung der effektiven magnetischen Momente und die Aufnahme von Massenspektren charakterisiert.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19926180128
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Beiträge zur Lanthanoidchemie. III Zur Kenntnis von 2-(Dimethylaminomethyl)ferrocenyl-Verbindungen des Samariums und Yttriums (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1957-1961 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Organolanthanide chemistry, samarium, yttrium ; 2-(dimethylaminomethyl)ferrocenyl compounds ; heterobimetallic organolanthanide chelate complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Contribution to Organolanthanoide Chemistry. III. On 2-(Dimethylaminomethyl)ferrocenyl Compounds of Samarium and YttriumEarlier results, indicating the ability of the bulky 2-(dimethylaminomethyl)ferrocenyl-group (FcN) to form thermocally stable, heterobimetallic organolanthanide compounds, were proved by the synthesis of organo-rare-earth derivatives (C5Me5)2Sm(FcN) (II), (C5H5)Sm(FcN)Cl (III), respectively (C5Me5)Y(FcN)Cl (IV) from the corresponding complex cyclopentadienyl rare-earth chlorides (C5Me5)2SmCl · KCl · THF, (C5H5)SmCl2 · THF and (C5Me5)YCl2 · KCl · 1,8 THF and 2-(dimethylaminomethyl)ferrocenyl lithium (FcN)Li (I) as organylating agent. The synthesized compounds were proved by elementary analysis, IR, 1H, 13C NMR and UV-VIS spectra as well as by measuring the magnetic moments and by mass spectroscopy.
    Notizen: Frühere Befunde, wonach die voluminöse 2-(Dimethylaminomethyl)ferrocenyl-Gruppierung (FcN) zur Bildung thermisch stabiler, heterobimetallischer Organolanthanoid(III)-Verbindungen befähigt ist, wurden durch die Darstellung der Organoseltenerd(III)-Derivate (C5Me5)2Sm(FcN) (II), (C5H5)Sm(FcN)Cl (III) und (C5Me5)Y(FcN)Cl (IV) aus den betreffenden komplexen Cyclopentadienyl-Seltenerd(III)-chloriden (C5Me5)2SmCl · KCl · THF, (C5H5)SmCl2 · THF bzw. (C5Me5)YCl2 · KCl · 1,8 THF und 2-(Dimethylaminomethyl)ferrocenyl-Lithium (FcN)Li (I) als Organylierungsmittel bestätigt. Die erhaltenen Verbindungen wurden durch Elementaranalysen, IR-, 1H-NMR-, 13C-NMR- und UV-VIS-Spektren sowie durch die Ermittlung der effektiven magnetischen Momente und die Aufnahme der Massenspektren charakterisiert.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19936191122
    Standort Signatur Erwartet Verfügbarkeit
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