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  • Polymer and Materials Science  (8)
  • locomotion  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 18 (1967), S. 112-116 
    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: Behaviour of materials for chemical apparatus at higher temperaturesFollowing an introductory survey of the essence and significance of static data (short-time and long-time tensile test at higher temperatures), the creep process associated with the latter is discussed and its effect on the service life of chemical apparatus indicated. On the basis of results of practical tests with nonferrous and ferrous metals, the statistical significance of conventional and desirable presentation results is discussed.
    Notes: Im Anschluß an einen einführenden Überblick über das Wesen und die Bedeutung statischer Kennzahlen (Kurzzeit- und Langzeit-Zugversuch bei höheren Temperaturen) wird der bei letzteren ablaufende Kriechvorgang erläutert und dessen Bedeutung für die „Laufzeit“ chemischer Apparate aufgezeigt. An praktischen Versuchsergebnissen (NE- und E-Metalle) wird die Aussagefähigkeit üblicher und zweckmäßiger Darstellungsmöglichkeiten Versuchsergebnisse diskutiert.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 15 (1964), S. 741-743 
    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: The corrosion resistance of titanium in nitric acid of high temperaturesCorrosion tests showed that, in nitric acid of a concentration ranging from 20 to 70 percent. and at temperatures ranging from 190 to 230° C, titanium has a corrosion rate of between 1 and 10mm pr. annum. This high corrosion rate can be avoided if a substance containing silicon is added to the nitric acid.
    Notes: Korrosionsversuche ergaben, daß Titan in Salpetersäure der Konzentrationen 20 bis 70% bei Temperaturen von 190 bis 230° C rnit Geschwindigkeiten zwischen 1 bis 10 mm/Jhr. abgetragen wird. Diese starke Korrosion läßt sich unterbinden, wenn der Salpetersäure eine siliciumhaltige-Substanz zugesetzt wird.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 275-281 
    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: Chemical and electrochemical reactions of iron sulfide and manganese sulfide in acid and neutral solutionsThe reactions which occur upon corrosion of massive iron sulfide and manganese specimens in perchloric acid and in neutral sodium chloride solution were elucidated by measurements of current-potential curves and by coulometric and analytical investigations on the processes. In acids the sulfides are dissolved by prevailing chemical reaction under evolution of H2S. Upon applying anodic overpotentials electrochemical reactions occur simultaneously, however, with such low velocity that the contribution to corrosion of the sulfides is insignificant. Upon applying cathodic overpotentials some hydrogen discharge is observed on iron sulfide but not on manganese sulfide.In 3% sodium chloride solution both sulfides corrode very slowly upon anodic polarization, forming elementary sulfur according to MeS = Me2+ + S + 2e- (Me = Fe or Mn). At high anodic potentials additional oxidation reactions occur in which three-valent iron and tetravalent manganese ions as well as sulfite and sulfate ions are formed.Iron sulfide and manganese sulfide inclusions can he isolated from steels only by electrochemical dissolution in neutral or weakly basic electrolytes, the potential during electrolysis must not be more positive than the corrosion potential of the sulfides.
    Notes: Durch Messen von Stromdichte-Potentialkurven und coulometrisch-analytische Untersuchungen wurden die Korrosionsreaktionen kompakter Eisensulfid- und Mangansulfidproben in Perchlorsäure, und in neutraler Natriumchlöridlösung aufgeklärt. In Säuren lösen sich beide Sulfide weitgehend chemisch unter H2S-Entwicklung. Daneben laufen bei anodischer Überspannung elektrochemische Reaktionen mit so geringer Geschwindigkeit ab, daß sie nur einen unbedeutenden Beitrag zur Korrosion des Eisensulfids und Mangansulfids liefern. Kathodisch werden am Eisensulfid Wasserstoffionen entladen. Diese Reaktion ist am Mangansulfid praktisch nicht feststellbar.In dreiprozentiger Natriumchlöridlosung korrodieren die beiden Sulfide bei anodischer Überspannung elektrochemisch sehr langsam unter Bildung elementaren Schwefels nach MeS = Me 2+ + S + 2e-(Me = Fe oder Mn). Im Bereich hoher anodischer Polarisation treten zusätzliche Oxydationsreaktionen auf, durch die dreiwertiges Eisen bzw. vierwertiges Mangan sowie Sulfit- und Sulfationen entstehen. Eisensulfid und Mangansulfid können aus Stahlen nur durch elektrochemisches Lösen der Stahlmatrix in neutralen oder schwach basischen Lösungen isoliert werden. Außerdem soll das Elektrolysepotential nicht positiver als das Ruhepotential dieser Sulfide sein.
    Additional Material: 7 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 540-545 
    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: Studies on the cathodic effect of iron sulfide and manganese sulfide on the corrosion of iron in a three percent sodium chloride solutionIn the galvanic element iron/sodium chloride solution/iron sulfide and in the element iron/sodium chloride solution/manganese sulfide, flushed with nitrogen or air, the sulfides become the cathode and the iron is anode. Upon short circuiting the electrodes a strong cathodic polarisation of the sulfides occurs. However, only if the iron is in contact with iron sulfide in the air-flushed sodium chloride solution the corrosion of the iron is enhanced because of considerable anodic polarisation. The corrosion of the iron electrode is increased corresponding to the increase in cathodic area.According to these results inclusions of iron sulfide or manganese sulfide act as local cathodes but cannot cause pitting corrosion of unalloyed steels in a neutral chloride solution.
    Notes: In den galvanischen Elementen Eisen/NaCl-Lösung/FeS und Eisen/NaCl-Lösung/MnS, durch die Stickstoff oder Sauerstoff strömt, stellen die Sulfide die Kathode und Eisen die Anode dar. Beim Kurzschließen der Elektroden werden die Sulfide stark kathodisch polarisiert. Das Eisen korrodiert aber lediglich im Kontakt mit Eisensulfid in belüfteter Natriumchloridlösung infolge merklicher anodischer Polarisation mit erhöhter Geschwindigkeit. Die gesteigerte Korrosion der Eisenelektrode entspricht aufgrund der reaktionsbestimmenden Sauerstoffdiffusion der Vergrößerung der kathodisch wirksamen Fläche.Nach diesen Ergebnissen können in unlegierten Stählen ausgeschiedene Eisensulfid- und Mangansulfideinschlüsse als Lokalkathoden keine Lochkorrosion in neutraler Natriumchloridlösung verursachen.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 5 (1985), S. 447-461 
    ISSN: 0886-1544
    Keywords: chemokinesis ; orthokinesis ; klinokinesis ; polymorphonuclear leucocytes ; locomotion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Evidence is presented to show that klinokinesis, which was previously demonstrated in bacteria and amoeba only, may also occur in metazoan cells. The chemotactic peptide formyl-Met-Leu-Phe (fMLP) elicited orthokinetic and klinokinetic responses of human blood-borne polymorphonuclear leucocytes (PMNs) under the test conditions used. Increased speed (orthokinesis) was due to an increase in the proportion of migrating cells as well as in the speed of the locomoting subset. The klinokinetic effect was manifested by a decrease in the klinolocomotion index, the mean angle of changes in direction ≥ 90°, and the frequency of turns ≥ 90°. The klinolocomotion index was inversely related to speed. This explains the synergistic effect of klinokinesis and orthokinesis in this system. Colchicine alone had and orthokinetic effect which was exclusively due to alterations in the proportion of migrating cells and it altered the turning behaviour without exerting a klinokinetic effect. However, colchicine had marginal orthokinetic and klinokinetic effects on fMLP-stimulated cells resulting in reduced translocation. The relationship between klinokinesis and mean angle or frequency of turns has been analysed. Klinokinesis was a substantial though not the major element of the chemokinetic response to fMLP under the conditions used. No other metazoan cells have been shown to possess such a complete pattern of responses, including orthokinesis, klinokinesis, and chemotaxis, which regulate locomotion.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 10-18 
    ISSN: 0886-1544
    Keywords: microtubules ; blebs ; locomotion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Colchicine-induced stimulation of polymorphonuclear leukocyte (PMN) locomotion is an interesting model because extension of blebs at the front occurs at a rate (about 2.4 μm/s) which is far above that reported for growth of actin filaments. The following cytoskeletal changes were observed in colchicine-treated PMNs: (1)a small increase in cytoskeleton-associated actin was noted, as well as a somewhate more pronounced increase in cytoskeleton-associated α-actinin, as compared with untreated or DMSO-treated controls. There was, however, no measurable increase in F-actin as determined by NBD-phallacidin blinding; (2)the values for the ratio (α-actinin/actin) are lower in PMNs treated with colchicine for 30 min, as compared with PMNs stimulated with fNLPNTL for 1 minute (non-polar ruffling cells) or 30 min (polarized locomoting cells); thus, this ratio may depend on the type of PMN motility; (3) in polarized PMNs F-actin was mainly located linearly all along the cell membrane; there was more intense staining at the front of the cells; (4) α-actining appeared to colocalize with F-actin at the leading front, but not with F-actin at the tail of polarized cells; (5) myosin was preferentially found at the rear part of polarized cells but not or only to a small extent at the front. Our data indicate a close functional correlation between microtubules and microfilaments. We speculate that F-actin in combination with α-actinin promotes expansion of pseudopods, whereas myosin combined with F-actin promotes contraction. In more general terms we suggest that different forms of PMN motility are generated by differential selective interaction of cytoskeletal compnents and variations in the composition of the cytoskeleton in different sites of the same cells. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 47-60 
    ISSN: 0886-1544
    Keywords: neutrophil granulocytes ; motility ; locomotion ; cell-shape ; cell-substratum adhesion ; f-Met-Leu-Phe ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Activation of the motile apparatus by chemokinetic factors cannot be reliably assessed in cells that are attached to a solid substratum because motility can be totally abolished by excessive adhesion. It is however, necesary to quantify the activation of the motile apparatus in order to analyze and understand chemokinetic responses.It was the purpose of the present work to establish morphological criteria that can be used to quantify motility in nonadherent (floating) neutrophils and to predict the locomotor response under conditions of limited adhesion. The proportion of neutrophils performing crawling-like movements (polarized cells) in suspension correlates very closely with stimulated locomotion at low to optimal concentration of f-Met-Leu-Phe, ie, under conditions of limited adhesion. Reduced locomotion at supraoptimal concentrations of f-Met-Leu-Phe has also morphological correlates. The major feature is the decrease in the proportion of neutrophils performing crawling-like movements and the corresponding appearance of cells that are motile but not polarized in suspension and that do not locomote on the substratum. Concentration-dependent changes in neutrophil length and in the proportion of polarized neutrophils with and without tail were also observed. The locomotor potential of neutrophils under conditions of limited contact with the substratum can be predicted on the basis of their motile behavior, in particular the proportion of cells showing crawling-like movements, in suspension. In combination with measurements of adhesion the procedure should permit a more complete analysis of the regulation of chemokinetic responses.
    Additional Material: 8 Ill.
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In the series glucose G, maltose G2, maltotriose G3 etc. the equilibria: 2 G2 = G3 + G (K1), G3 + G2 = G4 + G (K2) etc. are specifically catalysed by the enzyme amylomaltase. The equilibrated mixtures are analysed by chromatography and the equilibrium constants K1, K2 etc. are calculated. They rise from the value K1 = 0,9 asymptotically to a limiting value of ca. 1,05. Enthalpy, Entropy and free enthalpy of the reaction are (excepted the frist step) as expected nearly 0. The enzyme amylomaltase, as isolated from Escherichia coli ML (from Institute Pasteur, Paris) has a molecular weight of nearly 130 000 and a turnover of nearly 11 000 moles maltose per minute.
    Notes: In der Reihe Glucose G, Maltose G2, Maltotriose G3 usw. stellt Amylomaltase die Gleichgewichte: 2 G2 = G3 + G (K1), G3 + G2 = G4 + G (K2) usw. ein. Die Gleichgewichtsgemische werden chromatographisch analysiert und daraus die Gleichgewichtskonstanten K1, K2 usw. berechnet. Diese steigen vom Wert K1 = 0,9 ab bis zu einem Grenzwert von etwa 1,05 asymptotisch an. Enthalpie, Entropie und freie Enthalpie liegen, außer für den ersten Reaktionsschritt (K1), wie zu erwarten nahe bei 0. Das aus Escherichia coli (Stamm ML aus dem Institut Pasteur) isolierte Enzym Amylomaltase hat ein Molekulargewicht von etwa 130 000 und eine darauf bezogen Wechselahle von etwa 11 000 Mol Maltose pro Min.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 23 (1992), S. 299-304 
    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
    Notes: Untersuchungen an Flachzugproben und Behältern aus Vergütungs- und Feinkornbaustählen mit etwa halbelliptischen Oberflächenrissen haben gezeigt. Daß die Versagensspannung nach Verfahren des plastischen Versagens konservativ ermittelt wird. Während sie nach dem Ansatz von Harrison und dem Fließkriterium von Mises - unabhängig von der Rißtiefe - im Mintel um etwa 10% unterschätzt wird, bewerten die anderen untersuchten Verfahren (Mattheck, Chell) deutlich konservativer. Der Grad der Unterschätzung wächst von etwa 30 bzw. 40% bei mittleren Rißtiefen bis zu 70% bei tiefen Rissen. Für einseitigen Wasserstoffangriff auf der Rißausgangsseite ergaben sich i.a. die gleichen konservativen Bewertungen wie bei Luftumgebung.Die Untersuchung hat weiterhin gezeigt, Daß die Versagensspannung von Fluchzugproben unter Luft- und Wasserstoff-Atmosphäre mit etwa konstanter Rißtiefe mit guter Genauigkeit berechnet werden kann, wenn im Restquerschnitt der Mittelwert zwischen Streckgrenze und Zugfestigkeit als Fließspannung angesetzt wird.Es ist für ähnliche Bauteile zu erwarten, daß die erarbeiteten Ergebnisse auf Werkstoffe mit vergleichbaren Rißzähigkeits- und Festigkeitseigenschaften übertragbar sind.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 200-204 
    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: Strength behaviour of rupture disks under long-term stressIn sizing rupture disks of plastically deforming materials (Al, Cu, Ag, Ni, CrNi steels, Pb) one has to take into account not only the response pressure tolerances (which can amount to ± 10%) but also the loss of mechanical strength as a function of time and temperature. In addition, the type of attachment and the edge radius play an important part. Tests made with a brittle material - specially developed fine-grain graphite - have yielded highly promising results, so that 35% of all the rupture disks in a large chemical factory are now of graphite. The creep curves are very flat and the dispersion of creep values is but low.
    Notes: Bei der Auslegung von Berstscheiben aus plastisch verformbaren Werkstoffen (Al, Cu, Ag, Ni, CrNi-Stähle, Pb) muß neben der Toleranz des Ansprechdrucks (zulässig ± 10%) auch der zeit- und temperaturabhängige Festigkeitsabfall berücksichtigt werden. Außerdem spielen hierbei auch die Art der Einspannung bzw. der Kantenradius eine wesentliche Rolle. Versuche mit einem spröden Material - speziell entwickelter feinkörniger Graphit - verliefen erfolgreich, so daß in einem großen Chemiewerk gegenwärtig 35% aller Berstscheiben aus diesem Material sind. Die Zeitstandfestigkeitskurven verlaufen sehr flach und weisen nur eine geringe Streuung auf.
    Additional Material: 10 Ill.
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