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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 510-521 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rate of catalytic CO oxidation on Pt(100) and (110) surfaces at low pressures (≤10−4 Torr) and under isothermal conditions may exhibit sustained temporal oscillations which are coupled with periodic transformations of the surface structures between reconstructed and nonreconstructed phases, the latter exhibiting higher oxygen sticking coefficients and hence higher reactivity. With Pt(100) the two surface phases exhibit a much larger difference in reactivity (=oxygen sticking coefficient) than with Pt(110), which effect accounts for the qualitative differences in the oscillatory behavior: if two of the control parameters (say pO2, T) are kept fixed, the third (pCO) may be varied with Pt(100) over a fairly wide range without leaving the oscillatory region. Minor (〈1%) fluctuations of the partial pressures associated with the varying reaction rate are hence without any noticeable effect. Coupling between surface reaction and diffusion causes wave propagation of the surface phase transformations and therefore spatial self-organization, as demonstrated by scanning LEED experiments. With Pt(110), on the other hand, the oscillatory region is very narrow. In this case mass transport through the gas phase as caused by the small pressure variations associated with the reaction lead to synchronization between different parts of the surface. Computer simulations with the cellular automaton technique confirm qualitatively the experimental findings and support the conclusions reached.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 32 (1990), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immunoprecipitation of radioiodinated hairy cell leukaemia (HCL) cell lysates with monoclonal antibody (MoAb) HML-1. originally reported to recognize intraepithelial T cells, and with MoAb B-ly7, originally reported to react with HCL. led to identical biochemical characteristics. In SDS PAGE under reducing conditions, a major band of 143 kDa. a broad band ranging from 112 to 122 kDa. and two additional faint bands of 175 and 100 kDa could be determined. Deglycosylation of N-linked sugar moieties by treatment of immunoprecipitates with endoglycosidases indicated that the two main protein cores of the antigen are predominantly if not exclusively glycosylated by complex and hybrid types of oligosaccharide chains. Competitive binding inhibition demonstrated that both MoAb are directed against different epitopes. Immunohistochemically. the staining patterns obtained with both MoAb in normal tissues, in T-and B-cell lymphomas, and in HCL were identical except for a single case of HCL which was HML-1−/B-ly-7+, We conclude that MoAb HML-1 and B-1y7 recognize the same antigen.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 742-749 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Periodic modulations of oxygen pressure or temperature were applied in the catalytic oxidation of CO on a Pt(100) surface under isothermal, low pressure conditions. Transitions from aperiodic autonomous oscillations to regular phase-locked behavior could be observed. Computer simulations using a stochastic cellular automaton model yielded qualitatively similar results. The spatial distribution in both experiment and simulation varies essentially in phase over the whole surface area under the influence of the periodic perturbation, while wave propagation in the autonomous system causes more irregular overall behavior.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5328-5336 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The previously observed phenomena of temporal and spatial self-organization during the catalytic oxidation of CO on a Pt(100) surface were computer simulated by use of the cellular automaton technique. The underlying model is footed on the knowledge about the individual reaction steps (adsorption, desorption, surface structural transformation, etc.), which in turn formed the basis of a previous theoretical treatment in terms of the formulation and solution of a set of coupled differential equations. The present result nicely show the formation and propagation of two-dimensional patterns, and they reproduce qualitatively well all the experimental observations. The development of macroscopic patterns even with an a priori perfectly homogeneous surface is a particularly interesting effect.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Four monoclonal antibodies against antigens expressed differentially by the normal thymus epithelium, which define the cortical, medullary and subcapsular compartments, were used for immunohistological characterization of the epithelial cells in 14 thymomas. Furthermore, thymoma-associated lymphocytes were studied with monoclonal antibodies directed against T-lymphocyte differentiation antigens (CD1a, CD3, T-cell antigen receptor). Only four of the 14 thymomas could be classified into either medullary or cortical type thymoma based on the immunophenotype of epithelial cells. Ten cases escaped immunophenotypical classification due to co-expression of medullary and cortical antigens by the tumour cells. This aberration from the normal phenotype might indicate the failure of differentiation of such tumours. The immunophenotype of the associated lymphocytes, on the other hand, made it possible to classify the tumours as cortical (5 cases), mixed (2) and medullary (3) thymomas. Four thymomas escaped this classification scheme due to the absence of lymphocytes (2) or to a hybrid immunophenotype (2). Nevertheless, thymocytes of cortical type clearly predominated and were seen in all thymomas with associated lymphocytes. This feature may constitute a good diagnostic tool in differential diagnosis since, in 28 mediastinal or extramediastinal metastasis of tumours not derived from thymic epithelium and associated with various numbers of lymphocytes, none of them were found to contain CD1a positive lymphocytes.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 39 (1974), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 42 (1977), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bovine muscle samples were fractionated and assayed to assess the effects of high postmortem temperatures on lysosomal enzymes and muscle fragmentation values. Samples of the longissimus dorsi muscle were excised from both sides of six animals. One muscle was held at 37°C (HT) and the other was maintained at 2°C as control (C). The pH of the muscles was determined at 1, 4, and 12 hr postmortem. After 12 hr the muscles were homogenized and centrifuged to separate sedimen-table and unsedimentable fractions which were assayed for β-glucuronidase and cathepsin C activities. A fragmentation value was also determined for each sample. The pH of the HT samples dropped more rapidly and was significantly lower at both 4 and 12 hr. No detectable difference in total β-glucuronidase activity was observed between HT and C samples but the distribution was markedly altered as shown by significant differences in the percent of total activity that was unsedimentable (HT 〉 C, P 〈 0.025) and specific activities of the sedimen-table (HT 〉 C, P 〈 0.025) and unsedimentable (HT 〉 C, P 〈 0.025) fractions. For cathepsin C there was a significant drop in total enzyme activity (HT 〉 C, P 〈 0.005) resulting from an apparent degradation of the unsedimentable enzyme which had been released by the HT treatment. The fragmentation values were significantly different showing that the HT samples had probably undergone limited proteolysis resulting in a reduction of muscle fragment size after homogenization. These results add support for the role of lysosomal enzymes in postmortem tenderization.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 409 (2001), S. 785-790 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Nuclei undergoing fission can be described by a multi-dimensional potential-energy surface that guides the nuclear shape evolution—from the ground state, through intermediate saddle points and finally to the configurations of separated fission fragments. Until now, calculations have lacked ...
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of wildlife research 30 (1984), S. 259-264 
    ISSN: 1439-0574
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary This report discusses two primary liver tumours which developed spontaneously and which have not been described in roe deer before. These were a Haemangioma cavernosum in a liver celladenom and a solitary, primary malignes Lymphom which is best classified as a B-cell Lymphom.
    Abstract: Résumé Il est rendu compte de deux cas, inconnus jusqu'alors, de tumeurs hépatiques primaires, apparues spontanément chez le Chevreuil. Is s'agit, en l'occurence, d'un Hémangiome caverneux dans un Adénome de cellules hépatiques de même que d'un Lymphome primaire de nature maligne qui doit plutôt être classé comme un Lymphome B-cellulaire.
    Notes: Zusammenfassung Es wird über zwei bisher beim Reh nicht beschriebene spontan entstandene primäre Lebertumoren berichtet. Dabei handelt es sich um ein Haemangioma cavernosum in einem Leberzelladenom sowie um ein solitäres, primär malignes Lymphom, das am ehesten als ein B-Zell-Lymphom zu klassifizieren ist.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 253 (1975), S. 98-108 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Bei dieser Untersuchung der Oberflächeneigenschaften von ungeschlichteten, vakuumwärmebehandelten „Thornel-50”-Graphitfasern haben wir Tieftemperatur-absorption von Stickstoff und Argon mit Mikrogravimetrie und die massenspektroskopische Analyse angewendet. Es konnte gezeigt werden, daß die spezifische Oberfläche der Graphitfasern niedrig ist, von der Größenordnung 1 m2/g. Diese spezifische Oberfläche nimmt zunächst ab und wächst dann langsam an, wenn die Fasern zu immer höheren Temperaturen aufgeheizt werden. Die Gestalt der Adsorptionsisothermen und der Vergleich der Adsorptionsdaten für Fasern, die bei verschiedenen Temperaturen wärmebehandelt waren, die Analyse der Massenspektren der Gase, die beim Aufheizen entstehen, und die bekannten Größenabmessungen der Graphitkristalle legen streng die Annahme für drei Arten von Adsorptionsstellen an den Fasern nahe. Die Flächenanteile der drei Bereiche sind etwa 0,67, 0,26 und 0,07. Wärmebehandlung bei Vakuum verringert die oxidierten Kanten und erhöht die nichtoxidierte Oberfläche. Das Fehlen einer Hysterese bei hohen relativen Drucken läßt eine vernachlässigbare Zahl an großen Poren vermuten, die mit der Außenseite der Faser verbunden sind. Dagegen ist die Anwesenheit einer relativ hohen Zahl von Mikroporen anzunehmen. Der Vergleich der BET-Oberfläche, gemessen mit Stickstoff bei 77°K mit einer Berechnung, die auf einer scanningelektronenmikroskopischen Aufnahme beruht, führt zu einem Faserrauhigkeitsfaktorr = 3.
    Notes: Summary A study was made of the surface properties of unsized vacuum heat treated “Thornel–50” graphite fibers. The techniques used were low temperature N2 and Ar adsorption by microgravimetry, and mass spectrometry. The experiments showed that graphite fiber specific surface area was low — on the order of 1 M2/g. This specific surface first decreased and then increased slightly as the fibers were heated to higher and higher temperatures, The shape of the adsorption isotherms, comparison of adsorption data for fibers heat treated to different temperatures, analysis of the mass spectra of gases evolved during heating, and the known dimensions of the graphite crystallites provided strong evidence for three kinds of adsorption site patches on the fiber. These were identified as planar faces, edges (of the basal planes), and oxidized edges of oriented graphite crystallites in the fiber surface. The fractions of the fiber surface composed of these three patch types were ca. 0.67, ca. 0.26, and ca. 0.07. Vacuum heat treatment decreased the oxidized edge and increased the unoxidized edge surface. Lack of adsorption hysteresis at high relative pressures suggested a negligible number of large pores opening to the outside of the fiber. However, presence of a relatively large number of micropores was indicated. Comparison of the BET surface area obtained with nitrogen at 77°K with a calculation based on scanning electron microscopy indicated a fiber roughness factor of 3.
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