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  • 1
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    PANGAEA
    In:  Supplement to: Petró, Sandro Monticelli; Pivel, Maria Alejandra G; Coimbra, Joao Carlos; Mizusaki, A M P (2016): Paleoceanographic changes through the last 130 ka in the Western South Atlantic based on planktonic foraminifera. Revista Brasileira de Paleontologia, 19(1), 3-14, https://doi.org/10.4072/rbp.2016.1.01
    Publication Date: 2020-01-17
    Description: This work reconstructs Late Quaternary paleoceanographic changes in the western South Atlantic Ocean based on sedimentary core GL-77, recovered from the lower continental slope in the Campos basin, offshore SE Brazil. The studied interval comprises the last 130 ka. Changes in sea surface temperature (SST) and paleoproductivity were estimated using the total planktonic foraminiferal fauna and oxygen isotope analyses. The age model was based on the oxygen isotope record, biostratigraphic datums and AMS 14C dating. It was observed that the Pleistocene/Holocene transition occurs within Globorotalia menardii Biozone Y, and is not coeval with the base of Biozone Z. The range between summer and winter SST estimates is larger during the glacial period compared to interglacials. Three peaks of low SST around 70, 50 - 45 and 20 ka coincided with periods of enhanced SE trade winds. Despite faunal differences between the last interglacial (MIS 5e) and the Holocene, our SST estimates suggest that SSTs did not differ significantly between these intervals.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 2
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 2340 data points
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  • 3
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A study of the corrosion behaviour and corrosion inhibition of AA 6061 and AA 2014 metal matrix composites (MMCs) reinforced with alumina particles, during exposures to 0.1m NaCl solution is reported. Many tungsten and molybdenum-containing inorganic salts were tested as corrosion inhibitors, but only ammonium tetrathiotungstate afforded good inhibiting properties, particularly towards the AA 2014-based MMC. The corrosion behaviour of the composites in uninhibited or inhibited solutions was compared by different techniques to that exhibited by the corresponding matrices. The techniques adopted included weight loss measurements, electron probe microanalysis (EPMA), scanning electron microscopy (SEM), linear polarization resistance measurements, polarization curve recordings and current noise analysis. The analysis of the current fluctuations showed that different patterns of the time records were obtained during pit initiation, stable pitting and general corrosion. The power spectrum density plots exhibited f−α trends, with α values around 20dBdecade−1 when corrosion was mainly localized in pits, while values tending to zero were measured when general corrosion became dominant.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 45 (1983), S. 1073-1096 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The properties of nonlinear equations describing the solute and solvent transport across a simplified Patlak-Goldstein-Hoffman model (two membranes in series without unstirred layers) are investigated both analytically and numerically. The analysis shows that the principal coefficients measured in transport experiments in the presence of active transport are dependent on the experimental conditions. These ‘apparent’ system parameters are extensions of the corresponding parameters determined both in passive systems and in the linear Kedem-Katchalsky theory. Moreover, they are related to the local phenomenological coefficients of the single membranes of the array. Several relationships between measurable quantities and the local system parameters are indicated, allowing the planning of experiments aimed at the measurement of the latter. Data in the literature have been used to check the proposed volume flow equation.
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  • 5
    ISSN: 1573-708X
    Keywords: European Central Bank ; asymmetry ; optimal monetary policy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Although the existence of differences in economic structure across European countries is well known, their implications for the conduct of the single monetary policy in Stage Three of EMU have not yet been analyzed. This paper explores the issue on the basis of a two-country, rational-expectations, stochastic model characterized by asymmetric structural equations and a general formulation for monetary policy. Only if financial shocks are the main source of instability can heterogeneity in structures be neglected. When real shocks to aggregate demand prevail, their geographical distribution and the difference in the elasticity of aggregate supply are the key factors governing the response to structural differences. When supply shocks predominate, irrespective of their geographical distribution monetary policy should lean against the wind with more determination than if countries were identical. Differences in the transmission lag of monetary policy or some concern for growth when pursuing price stabilization reduce the size of the correction in monetary policy called for by structural asymmetries.
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  • 6
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rat thyroid follicles in both the normal and the inverted configuration have been cultured in suspension. It has been found that normal follicles (i.e., those having a structural organization similar to the follicles in vivo) express most functional properties of the thyroid gland. They trap iodide, synthesize, secrete, and iodinate thyroglobulin, and secrete thyroid hormone into the culture medium. On the contrary, in inverted follicles (i.e., those having a cell polarity reversed with respect to normal) we were unable to detect expression of some of these functions. We conclude that both the follicular organization and the proper cell polarity are needed for the full expression of thyroid functional properties.
    Additional Material: 4 Ill.
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  • 7
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Korrosion in Solarheizungssystemen. II. Korrosionsverhalten von AA 6351 in Wasser/Glykol-LösungenBei der vorliegenden Untersuchung wurde das Korrosionsverhalten der als Werkstoffe für Solarabsorberplatten verwendeten Metalle ermittelt. Dazu wurde die Korrosionsbeständigkeit von AA 6351 (1% Si, 0,6% Mg, 0,3% Mn, Rest Al) in nichtinhibierten Wärmeträgerflüssigkeiten wie Ethylen- und Propylenglykol/Wasser-Gemischen untersucht. Zur Langzeitprüfung wurden die Proben 60 Tage lang in reinen, mit Chlorid verunreinigten oder teilweise zersetzten Glykol/Wasser-Lösungen exponiert (80°C). Die Zersetzung der Wärmeträgerflüssigkeiten, die unter Praxisbedingungen saure Produkte liefern, wurde simuliert, indem die Ethylen- und Propylenglykol/Wasser-Gemische in Kontakt mit Kupfer 30 Tage am Sieden gehalten wurden.In Glykol/Wasser-Gemischen führten Chloride in niedrigen Konzentrationen (200 ppm) zu einer Beschleunigung der Korrosion von Aluminium um mehr als eine Größenordnung; in teilweise zersetzten Lösungen mit 143 oder 86 ppm Kupfer-II-Ionen war die Korrosion im Vergleich zu den reinen Lösungen um mehr als 2 Größenordnungen verstärkt.Bei den gravimetrischen Untersuchungen wurde teilweise Lochkorrosion beobachtet; die Stärke dieser Korrosion wurde aufgrund der größten und der mittleren Lochtiefe, der Lochdichte und der mittleren Lochgröße beurteilt.Der Einfluß der Wärmeübergangs auf die Korrosion der Al-Legierung und das Kontaktbad Kupfer/AA 6351 wurde gravimetrisch und elektrochemisch ermittelt. Danach wird durch den Wärmeübergang durch Aluminium das Lochkorrosionspotential des Metalls beträchtlich erhöht. Im Falle des Kontaktpaars Aluminium/Kupfer führte der Wärmeübergang zu verstärkter Kontaktkorrosion des Aluminiums, und zwar auch dann, wenn der Wärmeübergang durch das Kupfer erfolgte.Die Korrosionsgeschwindigkeiten des Aluminiums unter Kontaktkorrosionsbedingungen wurden aus den mittleren galvanischen Strömen berechnet; ihr Beitrag zur gesamten gravimetrisch ermittelten Korrosion war aber gering. Dieser Umstand ist ein Indiz dafür, daß in Lösungen mit geringer Leitfähigkeit die Gefahr des Kontakts zwischen verschiedenen Metallen nicht durch den Kontakt selbst bedingt ist, sondern vor allem dadurch, daß sich das edlere Metall in der gleichen Lösung wie das Aluminium befindet.
    Notes: A research was carried out in order to investigate the corrosion behaviour of the metals most commonly used as construction materials for solar absorber plates.With this view, an attempt was made to test the corrosion resistance of the aluminium alloy AA 6351 (nominal composition: 1% Si, 0.6% Mg, 0.3% Mn, the balance Al) towards common uninhibited heat transfer fluids, such as ethylene and propylene glycol/water mixtures.Long time gravimetric tests consisted in up to 60 day exposures of the aluminium specimens to pure, chloride-polluted, or degraded glycol/water solutions, at the temperature of 80°C. The degradation into acidic products, experienced by heat transfer liquids in service, was simulated by keeping the ethylene and propylene glycol/water solutions at their boiling temperature for 30 days, in contact with copper.In glycol/water solutions the presence of chlorides at low concentration (200 ppm) caused the aluminium corrosion rates to increase by more than one order of magnitude, while in degraded solutions, containing 143 or 86 ppm cupric ions, corrosion rates higher than two order of magnitude with respect to pure solutions were obtained.During the gravimetric tests, pitting corrosion was observed in some cases and its extent was rated by evaluating the deepest and the average metal penetration, the pit density and the average pit size.The influence of heat transfer on the alloy AA 6351 corrosion and on the couple copper/AA 6351 efficiency was evaluated by gravimetric and electrochemical tests. Heat transfer through aluminium was found to significantly increase the aluminium alloy pitting potential. On the contrary, it stimulated the aluminium galvanic corrosion, when applied on either aluminium or copper.Under galvanic coupling conditions, the aluminium corrosion rates calculated from the average galvanic currents were a very little contribution to the gravimetric corrosion rates. This demonstrates that in low conductive solutions the risk of matching such dissimilar metals as copper and aluminium does not reside in the galvanic contact itself, but mainly in the mere presence of the noblest metal in the same solution where aluminium is immersed.
    Additional Material: 4 Ill.
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  • 8
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The behaviour of some 3-methyl-l-butyne halo-derivatives towards Armco iron corrosion in 0.5m H2SO4 was examined by the analysis of dissolved iron and electrochemical methods. Their inhibitive performance was determined in relation to the introduced halogen atom with respect to the duration of the tests and temperature. At the same time, these effects were compared to those of 1-octyn-3-ol. In general, the results of the electrochemical methods were found to be in good agreement with those of solution analysis. The possibility of obtaining reliable corrosion data from electrochemical impedance spectroscopy measurements by simply applying the Stern-Geary equation is discussed.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-879X
    Keywords: microparticles ; platinum catalysts ; alumina support ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High resolution transmission electron microscopy analysis of Pt/Al2O3 catalyst prepared by deposition of platinum from mesitylene solution shows that the smallest metal particles on edges and corners migrate under the influence of the electron beam. Sintering is also promoted.
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  • 10
    ISSN: 1572-879X
    Keywords: oxidehydrogenation of propane ; monolith reactor ; packed-bed reactor ; alumina-supported vanadium oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The catalytic performance of aγ-Al2O3 -supported vanadium oxide catalyst in the oxidehydrogenation of propane to propylene was compared when the catalyst was used in the form of granules (packed fixed-bed reactor), and when the V2O5/γ-Al2O3 was coated in the form of a thin layer over a cylindrical ceramic support (monolith-type reactor configuration). A considerable enhancement of the catalytic performance was achieved in the latter case, because the consecutive reaction of propylene overoxidation, responsible for a remarkable decrease in selectivity at high conversions in packed-bed reactors, was minimized.
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