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  • 11
    Electronic Resource
    Electronic Resource
    Dielectric studies of the cure of epoxy matrix systems (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 1155-1167 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric spectroscopy was used to monitor the curing process of two epoxy resin systems. The basic system (system I) consisted of DGEBA (a difunctional epoxy) and a polyamide in a 50-phr mixture. In addition, a comparative analysis was performed on a high-performance resin system (system II) used primarily in unidirectional composite applications. This system contained TGDDM (a tetrafunctional epoxy) and DDS (a tetrafunctional amine) in a 25-phr mixture. The dielectric data were obtained using a simple yet functional sample cell electrode designed and constructed in the laboratory. For system I, isothermal dielectric data were used to determine apparent activation energies for the temperature range from 22 to 70°C. The data showed that the activation energy was a function of temperature and increased as the temperature of the cure increased. This indicated that the reaction mechanism was also a function of temperature. For system II, data were collected between 140 and 190°C and an overall activation energy for that temperature range was determined. The overall activation energies for both systems, calculated using dielectric spectroscopy, compared favorably to those obtained using differential scanning calorimetry. Also, using a wider frequency range (240 Hz to 2 MHz), Argand diagrams were constructed and modeled with the Cole-Cole empirical equation for systems with a distribution of relaxation times. This justified the calculation of average relaxation times, which could then be related to the bulk physical properties of the polymer, such as viscosity. Modified Argand diagrams, where ε″ is plotted against ε′ at one frequency as a function of time, were also constructed, which aided in the understanding of the curing processes for these thermosetting systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070310501
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  • 12
    Electronic Resource
    Electronic Resource
    Dielectric modeling of the curing process (1986)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 346-353 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric data from an epoxy resin system were used as the foundation for dielectric modeling of the curing process. This resin system (DGEBA-polyamide) was chosen as an easily processible model system. Dielectric average relaxation times, defined as the reciprocal of the angular frequency at which the loss component of the dielectric constant reaches a maximum, were determined for a 40°C isothermal cure. The changes in the average relaxation time through the cure exhibited similar behavior to those for viscosity, which inspired the correlation of the two properties. The dielectric relaxation time was modeled using a six-parameter model analogous to that used for viscosity. The model parameters were in turn associated with both intrinsic properties of the system and reaction kinetics describing the cure. The possibility of extending the relaxation time model for use with single-frequency data by means of a time-frequency correlation was also investigated. Combined, these two modeling methodologies provide a powerful constitutive approach for describing dielectric properties of thermosetting polymers during cure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760260504
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  • 13
    Electronic Resource
    Electronic Resource
    Sjögren's autoimmunity: how perturbation of recognition in endomembrane traffic may provoke pathological recognition at the cell surface (1998)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 11 (1998), S. 40-48 
    Details
    ISSN: 0952-3499
    Keywords: autoimmune disease ; Sjögren's syndrome ; lacrimal gland ; membrane traffic ; endocytosis ; protein sorting ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: CD4 T cell antigen recognition requires presentation by major histocompatibility complex Class II molecules (MHC II). B cell surface immunoglobulins recognize antigens independently of MHC II, but activation typically requires CD4 cell cytokines as accessory signals. Plasma membrane-endomembrane traffic in lacrimal gland acinar cells, targets of autoimmune activity in Sjögren's syndrome, may satisfy both requirements. The Golgi protein galactosyltransferase and the lysosomal proteins cathepsin B and cathepsin D appear at the plasma membranes during sustained secretomotor stimulation. The RNA transcription termination factor La, a frequent target of Sjögren's autoantibodies, appears in the acinar cell cytoplasm and plasma membranes during viral infection and during in vitro exposure to cytokines. MHC II cycle through endomembrane compartments which contain La, galactosyltransferase, cathepsin B and cathepsin D and which are sites of proteolysis. This traffic may permit trilateral interactions in which B cells recognize autoantigens at the surface membranes, CD4 T cells recognize peptides presented by MHC II, B cells provide accessory signals to CD4 T cells, and CD4 T cells provide cytokines that activate B cells. Acinar cells stimulate lymphocyte proliferation in autologous mixed cell reactions, confirming that they are capable of provoking autoimmune responses. Copyright © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Expression of M-cadherin protein in myogenic cells during prenatal mouse development and differentiation of embryonic stem cells in culture (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 201 (1994), S. 245-259 
    Details
    ISSN: 1058-8388
    Keywords: M-cadherin antibodies ; N-CAM ; Desmin ; Laminin ; Somite ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Molecules regulating morphogenesis by cell-cell interactions are the cadherins, a class of calcium-dependent adhesion molecules. One of its members, M-cadherin, has been isolated from a myoblast cell line (Donalies et al. [1991] Proc. Natl. Acad. Sci. U.S.A. 88:8024 - 8028). In mouse development, expression of M-cadherin mRNA first appears at day 8.5 of gestation (E8.5) in somites and has been postulated to be down-regulated in developing muscle masses (Moore and Walsh [1993] Development 117:1409 - 1420). Affinity-purified polyclonal M-cadherin antibodies, detecting a protein of approximately 120 kDa, were used to study the cell expression pattern of M-cadherin protein. It was first visualized in somites at E10 1/3 and could be confined to desmin positive, myotomal cells. At all subsequent prenatal stages, M-cadherin was only found in myogenic cells of somitic origin. The detection of the protein at E10 1/3 suggests a translational delay of M-cadherin mRNA of 1 to 2 days (E8.5 vs. E10 1/3). This was further supported by the finding that during differentiation of ES cell line BLC6 into skeletal muscle cells in culture, expression of M-cadherin mRNA can be detected 2 days prior to M-cadherin protein. During prenatal development, the pattern of M-cadherin expression changes: In E10 1/3 embryos and also in myotomal cells of later stages, M-cadherin is evenly distributed on the cell surface. In developing muscle masses (tested at E16 to E18), however, M-cadherin protein becomes clustered most likely at sites of cell-cell contact as indicated by double-labelling experiments: M-cadherin-staining is the positive image of laminin negative areas excluding the presence of a basal lamina at M-cadherin positive sites. Furthermore, M-cadherin is coexpressed with the neuronal cell adhesion molecule N-CAM which has been shown to mediate cell-cell contact in myogenic cells. In summary, our results are in line with the idea that M-cadherin might play a central role in myogenic morphogenesis. © 1994 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1002010308
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  • 15
    Electronic Resource
    Electronic Resource
    Zur Chemie der 1,2,4-Triazine, XII. Cycloadditionen mit Azabenzolen, XVII. Reaktionen von 1,2,4-Triazinen mit 6-(Dimethylamino)pentafulven (1985)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1263-1271 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of 1,2,4-Triazines, XII1). - Cycloaddition Reactions of Azabenzenes, XVII2). - Reactions of 1,2,4-Triazines with 6-(Dimethylamino)pentafulvene6-(Dimethylamino)pentafulvene (1a) reacts with 1,2,4-triazines 6 to give either by addition to C-5 of 6 2,5-dihydro-5-(1-pentafulvenyl)-1,2,4-triazines 7 or by a [4 + 2] cycloaddition reaction the 2-pyrindene derivatives 20/23. A [6 + 4] cycloaddition reaction between 1a and 6 could not be observed.
    Notes: 6-(Dimethylamino)pentafulven (1a) reagiert mit 1,2,4-Triazinen 6 entweder über eine Addition an C-5 von 6 zu 2,5-Dihydro-5-(1-pentafulvenyl)-1,2,4-triazinen 7 oder über eine [4 + 2]-Cycloaddition zu den 2-Pyrinden-Derivaten 20/23. Eine [6 + 4]-Cycloaddition zwischen 1a und 6 konnte nicht nachgewiesen werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198519850616
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  • 16
    Electronic Resource
    Electronic Resource
    Evidence for involvement of a nuclear envelope-associated RNA helicase activity in nucleocytoplasmic RNA transport (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 145 (1990), S. 136-146 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It seems well established that translocation of at least some mRNAs through the nuclear pore is (1) an energy-dependent process, and (2) dependent on the presence of the poly(A) segment attached to most mRNA species. We describe that RNA helicase (RNA duplex unwindase) activity is present in a nuclear envelope (NE) preparation, which also appears to be involved in nucleocytoplasmic RNA transport. This activity unwinds RNA : RNA hybrids. The helicase has a pH optimum of 7.5 and a temperature optimum of 30°C. Applying the sealed NE vesicle system, it was shown that duplex RNA species are readily released from the vesicles in an unidirectional manner, in contrast to single-stranded RNA, which is much slower transported into the extravesicular space. Attachment of a poly(A) segment to the RNA duplex additionally increases the efflux rate of this RNA. Efflux of duplex RNA but not efflux of single-stranded RNA was strongly inhibited by formycin B 5′-triphosphate. Our results suggest that, besides poly(A), duplex structures, if present in a given RNA, modulate and control the export of RNA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041450119
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  • 17
    Electronic Resource
    Electronic Resource
    Kinetics of expression of prion protein in uninfected and scrapie-infected N2a mouse neuroblastoma cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 11 (1993), S. 1-11 
    Details
    ISSN: 0263-6484
    Keywords: Prion protein ; prion gene expression ; scrapie ; N2a cells ; mouse neuroblastoma cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The scrapie prion protein, PrPSc, is formed from its isoform, the cellular PrPc. There is evidence available indicating that PrPSc is necessary component of the infectious prion particle to cause a series of transmissible spongiform encephalopathies. We have used immunocytochemistry and RNA blotting techniques to investigate if infection with prions results in an increased PrP gene expression. For the experiments we used N2a cells which had been infected with prions (ScN2a cells). We demonstrated by confocal laser scanning microscopy that PrP-protein was present in the nucleus (predominantly in the nucleoli) of ScN2a cells. Analysis of the PrP-mRNA levels both in N2a- and in ScN2a cells using cDNA encoding PrPc revealed no marked alteration of the mRNA steady state level between the two cell strains. Likewise, in run-off experiments no changes in either PrP-specific transcription or in general transcriptional activity were found. The half-life of PrP-mRNA was found to be identical in both cell strains (7 h). Taken together, these results show that PrPSc and /or PrPc is present in the nucleus (nucleoli) of ScN2a cells but does not display and effect on the expression of the PrP gene.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290110102
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  • 18
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    Seafloor Displacement after the 2011 Tohoku-oki Earthquake in the Northern Japan Trench Examined by Repeated Bathymetric Surveys (2017)
    Wiley-Blackwell
    Details
    Publication Date: 2017-12-01
    Description: We conducted multibeam bathymetric surveys crossing the northern Japan Trench offshore Sanriku, and examined seafloor displacement by means of the difference in bathymetry before and after the 11 March 2011 Tohoku-oki earthquake. The seafloor displacements were less than several meters in vertical displacement and less than 20 m in trench-normal horizontal displacement, consequently lower amplitude seafloor displacements were evaluated. Comparatively, the landward lower slope near the trench was uplifted, the middle slope was subsided, and the mid-slope terrace was depressed after the earthquake. Therefore, localized very large fault slip or very large submarine landslide is unlikely. Instead, smaller uplift of the lower slope near the trench extending broader along the trench seems to be plausible explanation for the devastating tsunami source in the northern Japan Trench area.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley-Blackwell on behalf of American Geophysical Union (AGU).
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