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  • 1
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Antimony-rich vein mineralisation is widespread in the German part of the Variscan orogenic belt. Mineralogical investigation of a representative suite of these deposits, coupled with fluid inclusion characterisation and microthermometry, permits a reconstruction of their genetic evolution. Two structural settings host antimony mineralisation: the cores or flanks of anticlinal zones and major lithological contrasts. Channelled migration of geothermal fluids through permeable rock sequences and later stagnation of fluids in cap-rock situations inside the anticlinal zones led to mineral deposition. The mineralising event is interpreted as relating to input of deep-sourced fluids during late-orogenic exhumation at the transitional stage between collision tectonics and the late-Variscan extensional regime. Fluid inclusion data, chlorite geothermometry and the presence of meneghinite as a characteristic Pb-Sb-sulfosalt mineral in a number of vein systems allows constraints on model P-T conditions at the onset of mineralisation to be made. These are as high as 390 to 440 °C at 0.6–1.0 kbar for the Saarsegen, Apollo and Schöne Freundschaft deposits, with lower temperatures of 320–340 °C being obtained for the Spes deposit. The fluid inclusion data indicate drastic fluid cooling during the mineralising event; minimum temperatures of approximately 150–220 °C are obtained for all deposits at the end of vein quartz formation, which coincided with deposition of stibnite and most of the Pb-Sb sulfosalts. Besides the formation of extensional quartz-stibnite-Pb-sulfosalt veins, the mineralising, low-salinity NaCl-KCl-rich high-temperature tectonic brines have overprinted sulfide assemblages within earlier siderite-(Cu)-Pb-Zn veins. This has led to replacement reaction textures and remobilisation of sulfide components within the vein systems. In contrast with the earlier siderite-(Cu)-Pb-Zn veins, neither the quartz-stibnite-sulfosalt nor the (Cu)-Pb-Sb sulfosalt assemblages were affected by Variscan deformation. Rather, they display characteristic extensional features crosscutting all earlier structures and can thus be assigned to a later phase of mineralisation. Fluid composition characteristics and structural criteria indicate formation in the latest part of the Variscan mineralisation cycle; a post-Variscan genesis being rejected on grounds of conspicuously diverging fluid characteristics. A comparison of antimony deposits in the Rheinisches Schiefergebirge with other late-orogenic deposits elsewhere in the European Variscan belt indicates a significant number of shared features, enabling them to be placed into a common model related to the onset of late-Variscan brittle extensional tectonics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 7758-7767 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The kinetics of the solid state chemical reaction of silver with amorphous As33S67 films in a conventional sandwich structure was measured by optically monitoring the change in thickness of the undoped chalcogenide. For the thermally stimulated process, the kinetics data indicate a two-stage process, with the second stage having a sublinear time dependence. The effect of broadband illumination is to reduce the activation energy by approximately one order of magnitude, but the photoinduced process still has two identifiable stages. In the case of the photostimulated process, rate coefficients and activation energies have been measured and the composition and structure of the reaction products have been determined by Rutherford backscattering spectroscopy (RBS). The RBS spectra obtained at different stages of the photoinduced reaction process show a step-like form for the Ag concentration profile during the course of the reaction and indicated a homogeneous distribution of Ag in the final reaction products, the Ag concentration being 19.5 at. %. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2606-2612 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Control of the orientation of thin Pd films on (100) SrTiO3 surfaces was obtained by changing the growth temperature. In particular, a three-step growth method was applied to deposit thin single-crystal Pd films on single-crystal (100) SrTiO3 surfaces. This was realized by first growing epitaxial Pd seeds at elevated temperatures. Subsequently, the seeds were overgrown at room temperature by polycrystalline Pd which fully covered the substrate at a low thickness. Annealing of these films promoted growth of the epitaxial seeds, resulting in single-crystal Pd films: (100) SrTiO3(parallel)(100) Pd, [010] SrTiO3(parallel)[010] Pd. The three-step growth method turned out to be a useful method to overcome surface roughening and the creation of crystalline imperfections in thin Pd films. This is essential for the growth of thin metallic epitaxial buffer layers. The microstructure of the films was analyzed by reflection high-energy electron diffraction, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Terra nova 13 (2001), S. 0 
    ISSN: 1365-3121
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Transient mid-Cretaceous thermal uplift induced by lateral heating from passing oceanic lithosphere is often invoked as a mechanism for the formation of the Côte d’Ivoire–Ghana basement ridge in the Equatorial Atlantic. This heating event should have affected mid-Cretaceous sedimentary rocks along the ridge. However, organic maturity and clay mineral data on the thermal evolution of these rocks suggest that burial temperatures did not exceed 80 °C and that palaeo–geothermal gradients are not anomalous. Optical petrography and the stratigraphic pattern of temperature-sensitive parameters indicate that higher palaeotemperature estimates are related to admixtures of preheated, detrital organic and inorganic matter. Erosion brought the sediments to their present shallow burial depths. Lack of evidence for significant thermal alteration implies that either thermal exchange between oceanic and continental lithosphere along the Côte d’Ivoire–Ghana Transform Margin was negligible, or that lateral heating by oceanic lithosphere was not strong enough to affect the sedimentary cover of the basement ridge.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 404-407 (Aug. 2002), p. 691-696 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1433-044X
    Keywords: Schlüsselwörter Pigmentierte villonoduläre Synovialitis ; Poplitealzysten ; Gelenktumor ; Key words Pigmented villonodular synovitis ; Popliteal cyst ; Joint tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Pigmented villonodular synovitis (PVNS) is a disease that involves the lining of joints, bursae and tendon sheaths. The incidence is low and estimated to be 1.8 patients per million population. The cause of PVNS is unclear and discussed to be either inflammatory or neoplastic. PVNS has been described in 2 forms different for prognosis and treatment (nodular and diffuse). The articular form almost appeares in the knee joint as we describe below in a 14 year-old patient. PVNS was first defined in 1941 by Jaffe e.a. [7]. Because of the uncommon occurence of the disease it is difficult to amass patient series to allow confirmed statements on therapy and outcome. Larger patient series raise out of long periods of time. Differences in outcome and recurrence rates exist for the nodular and diffuse form. Clinical findings are moderate pain and swelling of joints due to effusion and synovial proliferation. Magnetic resonance imaging shows typical findings. Surgical procedures are recommended as open or arthroscopic synovectomy for the diffuse form of PVNS, local excision for the nodular form and arthrodesis or prosthetic replacement for joint destruction.
    Notes: Zusammenfassung Die pigmentierte villonoduläre Synovialitis (PVNS) ist eine Erkrankung der Gelenksynovialis, Bursen und Sehnenscheiden mit geringer Inzidenz (1,8/1 Mio. Einwohner). Ätiologisch wird sowohl ein chronisch-entzündliches Geschehen als auch ein neoplastischer Ursprung diskutiert. Prognostisch und therapeutisch relevant ist die Unterteilung in die diffuse und die lokalisiert-noduläre Manifestation, deren bevorzugte und meist einzige Lokalisation das Kniegelenk ist. Auch im vorliegenden Fallbericht wird über die monoartikuläre noduläre Manifestation im Kniegelenk eines 14jährigen Patienten berichtet. Die Erstbeschreibung der PVNS stammt von Jaffe et al. aus dem Jahre 1941 [7]. Aufgrund der geringen Inzidenz sind durch große Fallzahlen gesicherte Aussagen zu Therapie und Prognose in der Literatur selten und betreffen retrospektiv analysierte Patientenkollektive aus großen Zeiträumen. Gesichert ist die prognostische Relevanz der Manifestationsform (diffus oder nodulär ). Klinische Leitsymptome sind meist moderate Schmerzen und Schwellungszustände des Gelenks, zum einen bedingt durch einen intraartikulären Erguß, zum anderen im fortgeschrittenem Erkrankungsstadium bedingt durch die pathologische Gewebezunahme. Die spezifische Diagnostikmethode der Wahl ist die Magnetresonanztomographie ( MRT ). Das stadien- und manifestationsorientierte Vorgehen umfaßt an operativen Verfahren die offene oder arthroskopische Synovektomie im Falle der diffusen Erscheinungsform, die lokale Tumorexstirpation bei nodulärem Befall, weiter bei fortgeschrittener Erkrankung die Gelenkresektion mit Arthrodese oder Prothesenersatz.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1615-6102
    Keywords: Cell density ; Ceratodon purpureus ; Protoplasts ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Determinations of plant or algal cell density (cell mass divided by volume) have rarely accounted for the extracellular matrix or shrinkage during isolation. Three techniques were used to indirectly estimate the density of intact apical cells from protonemata of the mossCeratodon purpureus. First, the volume fraction of each cell component was determined by stereology, and published values for component density were used to extrapolate to the entire cell. Second, protonemal tips were immersed in bovine serum albumin solutions of different densities, and then the equilibrium density was corrected for the mass of the cell wall. Third, apical cell protoplasts were centrifuged in low-osmolarity gradients, and values were corrected for shrinkage during protoplast isolation. Values from centrifugation (1.004 to 1.015 g/cm3) were considerably lower than from other methods (1.046 to 1.085 g/cm3). This work appears to provide the first corrected estimates of the density of any plant cell. It also documents a method for the isolation of protoplasts specifically from apical cells of protonemal filaments.
    Type of Medium: Electronic Resource
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