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  • 2015-2019  (95)
  • 1975-1979  (19)
  • 1965-1969  (10)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 16 (1978), S. 239-246 
    ISSN: 1432-0630
    Keywords: 72.40 ; 73
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Indium oxide films doped with tin (ITO-films) have been hf-sputtered from an 80 at-%In2O3/20 at-%SnO2 target onto glass substrates. The sputter atmosphere contained mainly argon (10−2Torr) with addition of oxygen (0≦p O 2≦2·10−2Torr). The sputtered films aren-conductors. The conductivity and density of charge carriers depend on the oxygen content of the sputter gas. They could be varied by two orders of magnitude. In air or in oxygen atmosphere the films oxidize at the surface and for a certain depth beneath the surface, thus decreasing the conductivity. The Hall mobility of the sputtered films is smaller (≈10 cm2V−1 s−1) than one observes at ITO films produced by CVD sparaying or other methods. The conductivity of as sputtered films approached maximum values of about 1000Ώ−1cm−1.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-03-04
    Description: The boron isotope (δ11B) composition of marine calcifiers is considered to be one of the most reliable pH proxies, enabling us to reconstruct past ocean pH and infer on the associated changes in carbon budget involved (e.g. Gut- jahr et al. 2017). The application of the commonly used δ 11 B archives such as foraminifera or corals is however mostly limited to the Cenozoic due to insufficient preservation or incomplete geological records. Brachiopods have a promising potential for extending our knowledge on seawater pH evolution throughout the entire Phanerozoic considering their high abundance in the fossil record and its origin dating back to the early Cambrian. Moreover, their shell is composed of low-magnesium calcite, rendering brachiopods more resistant to post-depositional di-magenetic alteration of its primary chemical signal (e.g. Brand et al. 2012). Additionally, even today they present an extant and widespread taxa, allowing for an assessment of the controls on boron isotope incorporation into brachiopod calcite and possible distortions of the signal due to vital effects or other processes. We present a detailed exploration of boron isotope systematics in three different brachiopod species (Magellania venosa, Terebratella dorsata, Pajaudina atlantica) cultured under controlled laboratory settings for over a year. Our experimental setup includes a control (pH = 8.15) and two pH treatments (pH = 7.6 and 7.35), and we provide both bulk MC-ICP-MS as well as high spatial resolution SIMS data of the shell material. Our results indicate that boron incorporation is primarily driven by vital effects related to their ability to regulate calcifying fluid pH in response to ambient changes, which we further validate by in vivo microelectrode measurements (e.g. Stumpp et al. 2012). Despite internal buffering, the local pH at calcification sites systematically decreases with seawater pH, and hence is impacted by ocean acidification. This not only suggests that brachiopod shells serve as useful and conservative recorders of past ocean pH trends, but also provides new insights into mechanisms that may have enabled brachiopod survival throughout several major environmental crises in the past. Our findings have implications for past climate studies, as well as research on calcification processes and physio- logical adaptations to environmental change (e.g. the actual global ocean acidification). Brand, U., Posenato, R., Came, R., Affek, H., Angiolini, L., Azmy, K. and Farabegoli, E., 2012. The end-Permian mass extinction: A rapid volcanic CO2 and CH4-climatic catastrophe, Chem. Geol. 323, 121-144. Gutjahr M., Ridgewell A., Sexton P.F., Anagnostou E., Pearson P.N., Pälike H., Norris R.D., Thomas E., and Foster G.L., 2017. Very large release of mostly volcanic carbon during the Palaeocene-Eocene Thermal Maximum, Nature 548, 573-577. Stumpp M., Hu M.Y., Melzner F., Gutowska M., Dorey N., Himmerkus N., Holtmann W.C., Dupont S.T., Thorndyke M.C., and Bleich M. Acidified seawater impacts sea urchin larvae pH regulatory systems relevant for calcification, PNAS 44: 18192-18197.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 3
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 11 (1978), S. 452-454 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Since a major step in the formation of gall-stones appears to be the bacterial 7-dehydroxylation of allocholic acid, it is reasonable to assume that the reduction or elimination of the bacteria responsible for the conversion might interfere with gall-stone formation. Because of its well-known ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 1 (1979), S. 1443-1450 
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Für die Kompressionsgleichung (s − a) (p + b) = C wurden die drei Hyperbelkonstanten a, b, und C interpretiert und ihre Abhängigkeit vom Mischungsverhältnis zweier Substanzen untersucht. Die Grö\e b wurde als Verformungsspannung bezeichnet, sie kann mit der Flie\grenze eines Materials in Beziehung gesetzt werden. In einer Tablettenrezeptur kann der Anteil an verformtem Arzneistoff mit Hilfe der Konstanten b abgeschätzt werden.
    Notes: Abstract The three hyperbolic constants a, b and C were interpreted for the compression equation (s − a) (p + b) = C. Their dependence upon the mixture ratio of two substances was investigated. The quantity b was designated as deformation strain, it can be related to the yield point of a material. The proportion of deformed drug in a tablet formulation can be estimated by means of the constant b.
    Type of Medium: Electronic Resource
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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: Interactions between creep deformation and hot gas corrosionThe paper starts with a short explanation of the basic processes during the high temperature corrosion and of deformation under creep stress.Corrosion may give rise to an increase or a decrease of creep resistance, or it may result in an increase of the stress applied. The individual mechanisms are explained and, as far as possible, illustrated by examples. As a rule, however, several factors act simultaneously. The concerted actions is further complicated by back effects of a creep deformation on the corrosion processes. In the case of iron and nickel base alloys there exist obviously critical strain rates beyond which corrosion is enhanced and then proceeds more pronouncedly at the grain boundaries. It is also possible that then internal corrosion processes are triggered, in particular, in the grain boundary regions.While a qualitative assessment of the relationships between corrosion and creep deformation is possible, the feasibility of a quantitative description is still far away. As a rule, however, the aspect of a strength decrease will prevail although, in principle, corrosion may give rise to a strengthening, too.
    Notes: Einleitend werden kurz die Grundvorgänge der Heißgaskorrosion und der Verformung unter Zeitstandbeanspruchung erläutert.Die Korrosion kann den Kriechwiderstand erhöhen oder erniedrigen oder aber auch die anliegende Spannung vergrößern. Die einzelnen Mechanismen werden erläutert und - soweit möglich - durch Beispiele belegt. In der Regel wirken jedoch gleichzeitig mehrere Faktoren ein. Das Zusammenspiel wird durch Rückwirkungen der Kriechverformung auf die Korrosionsvorgänge weiter kompliziert. Für Eisen- und Nickelbasislegierungen gibt es offenbar kritische Dehngeschwindigkeiten, bei deren Überschreiten die Korrosion verstärkt und stärker korngrenzenorientiert abläuft. Auch innere Korrosionsvorgänge können dadurch besonders im Korngrenzenbereich ausgelöst werden.Während die Zusammenhänge zwischen Korrosion und Kriechverformung qualitativ überschaubar sind, liegt die Möglichkeit einer quantitativen Beschreibung noch in weiter Ferne. In der Regel werden die „Negativ-Punkte“ überwiegen, obgleich im Prinzip die Korrosion auch eine Verfestigung bewirken kann.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Some Substitution Reactions of Trimeric ThioformaldehydeTreatment of s-trithiane with n-butyllithium results in the formation of lithium salts of carbenium ions. Their reactions with the halo-functional compounds lead to mono- or multi-substituted trithianes besides lithium chloride.
    Notes: Die Behandlung von s-Trithian mit n-Butyllithium führt zu Lithiumsalzen von Carbanionen. Bei der Umsetzung mit den halogenfunktionellen Verbindungen CH3J. (CH3)3SiCl, (CH3)3GeCl, (CH3)3SnCl und (CH3)2SiCl2 reagieren diese unter Abspaltung von LiCl zu ein- oder mehrfach substituierten s-Trithianen.
    Type of Medium: Electronic Resource
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