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  • 1
    Electronic Resource
    Electronic Resource
    In-vivo stimulation of rat pancreatic acinar cells by infusion of secretin (1985)
    Springer
    Cell & tissue research 242 (1985), S. 633-639 
    Details
    ISSN: 1432-0878
    Keywords: Secretin ; Pancreas ; Enzyme secretion ; Protein synthesis ; Fine structure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Infusion of synthetic secretin in conscious unrestricted rats for periods up to 24 h was used to study the structural and functional adaptation of pancreatic acinar cells to this secretagogue. Initial dose-response studies established 16 clinical units (CU) per kg and h (corresponding to 4.64 ug x kg-1 x h-1) as optimal dose for persistent stimulation of enzyme discharge. Infusion of this dose led to a slow but progressive depletion of enzyme stores with minimal content by 12 h stimulation. As a result of persistent stimulation total protein synthesis in the acinar cells increased after a lag period of 3 h and reached maximal values 90% above controls by 6 and 12 h secretin infusion. No structural equivalent for pronounced fluid and bicarbonate secretion was observed for either acinar or duct cells over the entire dose range (1 to 64 CU x kg-1 x h-1) and infusion period (1–24 h), except an increased number of coated vesicles in duct cells. Discharge of enzymes from acinar cells was paralleled by a high frequency of exocytotic images at the luminal plasma membrane and was accompanied by the occurrence of membrane fragments in the luminal space, especially after 3 and 6 h secretin infusion. An increased number of lysosomal bodies at these time points especially in the vicinity of the Golgi complex was interpreted in relation to membrane recycling following massive exocytosis. This pattern of structural and functional adaptation of acinar cells following secretin infusion corresponds to previously described changes following caerulein and carbamylcholine stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225430
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  • 2
    Electronic Resource
    Electronic Resource
    In-vivo stimulation of rat pancreatic acinar cells by infusion of secretin (1985)
    Springer
    Cell & tissue research 242 (1985), S. 641-644 
    Details
    ISSN: 1432-0878
    Keywords: Secretin ; Pancreas ; Protein synthesis ; Enzyme synthesis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intravenous infusion of synthetic secretin for periods up to 24 h in conscious rats was combined with invitro amino acid incorporation in isolated pancreatic lobules and high-resolution separation of individual enzyme proteins by two-dimensional isoelectric focusing and SDS gel electrophoresis. With this method persistent changes in the biosynthesis of ten enzyme and isoenzyme proteins can be studied as a result of prolonged secretin stimulation. Three major patterns of response were observed: progressive increases in the synthetic rates were found in six out of ten enzyme proteins with most pronounced changes in the synthetic rates of lipase (4.10-fold increase), two forms of proelastase (2.80-fold increase, respectively), the two acidic forms of trypsinogen and chymotrypsinogen (2.60-and 2.40-fold increase, respectively), and of ribonuclease (2.30-fold increase). Only moderate changes (1.30- to 1.90-fold increase) occured in the synthetic rates of four isoenzymatic forms of procarboxypeptidase and the basic forms of chymotrypsinogen and trypsinogen, respectively. No absolute change in the rate of synthesis was observed in both forms of amylase. These data obtained after secretin stimulation differ significantly from previous results after caerulein stimulation, but it is not clear so far whether this is due to differential effects of the two second messengers released by each of the hormones on the level of transcription or translation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225431
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  • 3
    Electronic Resource
    Electronic Resource
    Grundlegende Betrachtungen zur Eigenspannungsanalyse an Keramik-Metall-Verbunden mittels FEM (1993)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 24 (1993), S. 20-25 
    Details
    ISSN: 0933-5137
    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: Fundamental Investigations of Residual Stresses in Metal-Ceramic-Joints by FEMThe reduction of damages in metal-ceramic-joints caused by residual stresses is of essential significance. Therefore, a model was created to simulate the behaviour of metal-ceramic-joints under thermal stress. In this paper, results of fundamental investigations are presented.
    Notes: Eigenspannungen in Metall-Keramik-Verbunden führen häufig zu deren vorzeitigem Versagen. Im vorliegenden Beitrag werden Ergebnisse aus Grundlagenuntersuchungen vorgestellt, bei denen der Einfluß wesentlicher Werkstoffkennwerte untersucht sowie ein Vergleich der Rechenergebnisse mit Laboruntersuchungen vorgenommen wurde.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19930240115
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanische Eigenschaften der durch thermisches Spritzen hergestellten unidirektionalen Faserverbundwerkstoffe (1992)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 23 (1992), S. 99-106 
    Details
    ISSN: 0933-5137
    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: Mechanical properties of unidirectional fibre-reinforced composites made by thermal sprayingBasic mechanical and technological properties of continuous fibre-reinforced metal-matrix composites made by thermal spraying are presented. The simple model of continuum theory has been used for the calculation of composite properties parallel to the fibre direction [1]. Taking into account the results obtained the theoretical analysis of composite failure modes and difference between praxis and theory is carried out. Problems concerning the properties measurements of thermally sprayed composites are discussed and their influence on the results is analysed as well. The comparison between the theoretically estimated composite strength and the experimental results is presented. The directions of future research work to improve the composite mechanical properties are also given.
    Notes: Die mechanischen und technologischen Eigenschaften der durch thermisches Spritzen hergestellten metallischen Verbundwerkstoffe mit kontinuierlichen, unidirektionalen Fasern werden vorgestellt. Mit Hilfe einfacher Modelle der Kontinuumstheorie werden die theoretisch erreichbaren Werte der mechanischen Eigenschaften, unter einachsiger Zugbelastung in Faserrichtung [1], abgeschätzt. Die experimentell erhaltenen Ergebnisse werden mit den theoretisch ermittelten verglichen. Es folgt eine Analyse der möglichen Abweichungsursachen zwischen den einzelnen Ergebnissen, wobei die herstellungs- und prüfungsbezogenen Aspekte im Mittelpunkt des Interesses stehen. Die Relation Theorie-Experiment dient weiterhin als Basis für die Untersuchung der Optimierungsmöglichkeiten der mechanischen Eigenschaften betrachteter Faserverbundwerkstoffe. Es ergeben sich Richtungen für weitere Forschungsarbeiten, die eine bessere Spezifizierung der vorhandenen Modelle sowie auch der Verbesserung der mechanischen Eigenschaften der durch thermisches Spritzen hergestellten Faserverbundwerkstoffe ermöglichen sollen.Die Untersuchungen beziehen sich auf thermisch gespritzte, stahlfaserverstärkte NiCr-Legierungen; die hier als Beispiel durchgeführte Analyse betrifft das Verbundwerkstoffsystem NiCr19Al6Si/25%-X12CrNi177-Faser (1.4310).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19920230308
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  • 5
    Electronic Resource
    Electronic Resource
    Möglichkeiten und Grenzen zur Beschreibung der mechanischen Eigenschaften von Faserverbundwerkstoffen mit Hilfe der Kontinuumstheorie (1992)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 23 (1992), S. 54-66 
    Details
    ISSN: 0933-5137
    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: Continuum theory - its potential and limits for the properties description of fibre-reinforced compositesThe different models of continuum theory for the prediction of mechanical properties of composites are presented. The analysis is carried out for the continuous fibre-reinforced unidirectionally loaded composites and concerns basic mechanical properties. The aspects of metal and/or ceramic-matrix composites are explained and their influence on the possible differences between the experimental results and theoretical calculation is analysed. The reasons of deviations concerned to the models and the experiments are also discussed. An algorithm to adopt the rule of mixture for the calculation of tensile strength of unidirectional loaded fiberreinforced composite is presented. The matrix-fibre interrace properties as well as fibre and matrix behaviour are included in this algorithm. The correlation between the failure mode of composites and its properties is analysed as well. The stress-strain behaviour of the composites concerning failure modes and the phases properties is fully described. The different models which offer the better description of the composite properties than the rule of mixture are also presented and discussed.
    Notes: In diesem Artikel werden Möglichkeiten und Grenzen der Anwendung der Modelle der Kontinuumstheorie für die Berechnung der mechanischen Eigenschaften eines Verbundwerkstoffs am Beispiel des Einsatzes der Mischungsregel für die Ermittlung der Zugfestigkeit des unidirektionalen Faserverbundwerkstoffs vorgestellt. Die werkstofftechnischen Aspekte der Metall- und Keramik-Matrix-Faserverbundwerkstoffe werden dargelegt und die damit verbundenen Abweichungen der experimentellen Ergebnisse van den theoretisch ermittelten Werten analysiert. Die modellbedingten Fehler werden den anderen Fehlern in dem System Mensch-Modell-Experiment gegenübergestellt. Es wird ein Algorithmus zur Anpassung der Mischungsregel für den Einsatz bei der Berechnung der Zugfestigkeit für die unidirektionalen Faserverbundwerkstoffe vorgestellt. Hierbei werden neben den Beziehungen zwischen den Mechanischen Eigenschaften der Faser und Matrix die Eigenschaften der Grenzfläche berücksichtigt. Die Korrelation zwischen den Versagensarten und Verbundeigenschaften wird ebenso angesprochen. Außerdem wird die Ermittlung der Spannungs-Dehnungs-Kennlinien des Verbundwerkstoffes unter Berücksichtigung der genannten Aspekte beschrieben. Zum Schluß werden die Vorteile anderer Modelle gegenüber der Mischungsregel und die Möglichkeiten einer genaueren Berechnung der mechanischen Eigenschaften vorgestellt.Alle durchgeführten Betrachtungen betreffen unidirektionale Faserverbundwerkstoffe (Langfaser), die in Richtung der Faser auf Zug belastet werden.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19920230207
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  • 6
    Electronic Resource
    Electronic Resource
    Einfluß der Belastungsfrequenz auf die Lebensdauer von Punktschweißverbindungen (1983)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 14 (1983), S. 19-24 
    Details
    ISSN: 0933-5137
    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: The Effect of Different Test Frequencies on the Lifetime of Spot-Welded JointsIn general lifetime prediction of welded joints is basing on S-N-curves where the influence of the variation of the S-N-curve is not taken into consideration. Moreover, it is not possible to specify the valid frequency range for the endurance limit of spot-welded joints.The test frequency defines the load velocity as a function of the phase relation of the strength. At the same time, the strength properties of the base material, the HAZ and the weld nugget are affected by load velocity. This means that the endurance limit of spot-welded joints is a function of the test frequency.This correlation was confirmed with tests on spot-welded deep-drawing sheets of R St 1403 (similar to AISI C 1008).In the report test results and the different fracture mechanisms are presented.
    Notes: Eine Lebensdauervorhersage für Punktschweißverbindungen ist grundsätzlich an Hand von Wöhler-Diagrammen möglich. Hierbei bleibt jedoch der Einfluß der Belastungsfrequenz unberücksichtigt, so daß es nicht möglich ist, die Lebensdauer der Verbindung bei unterschiedlichen Frequenzen anzugeben.Durch die Belastungsfrequenz ist die Verformungsgeschwindigkeit als Funktion der Phasenlage der Kraft vorgegeben. Gleichzeitig sind die Festigkeitswerte des Grundmaterials, der WEZ und der Schweißlinse von der Verformungsgeschwindigkeit abhängig. Aus diesem Grund ist die Dauerschwingfestigkeit von Punktschweißverbindungen als Funktion der Belastungsfrequenz anzusehen. Dieser Zusammenhang stimmt überein mit Untersuchungen an Punktschweißverbindungen aus RSt-1403. In diesem Bericht werden die Ergebnisse dargestellt und die unterschiedlichen Bruchmechanismen an Hand rasterelektronenmikroskopischer Untersuchungen erläutert.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19830140107
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