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  • Polymer and Materials Science  (8)
  • Life and Medical Sciences  (5)
  • 25.70.Jj  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Evidence for quasi-fission in40Ar+208Pb collisions near the coulomb-barrier (1987)
    Springer
    The European physical journal 326 (1987), S. 313-326 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.Jj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Fission-fragment angular distributions were measured in the reaction of40Ar with208Pb near the fusion barrier. For nearly symmetric mass-/charge splits we find angular distributions symmetric around θ=90 degrees, however, with unusually large anisotropies. These develop gradually into forward-backward asymmetric distributions as one moves away from mass-/charge symmetry. This indicates that non-compound fission (‘quasi-fission’) competes with true fusion-fission. The relative contribution of quasi-fission to the total fission cross section is somewhere between 51 and 85%. In the framework of the extra-push model this is equivalent to an extra-extra push energy for compound-nucleus formation inside the true fission saddle point of 4〈E xx 〈9 MeV in agreement with a recent empirical parametrization of fusion-barrier shifts based on fusion-fission cross sections. On the basis of cross sections for fusion-evaporation residues it had previously been concluded that fusion of40Ar with Pb isotopes occurs unhindered. Possible reasons for this apparent discrepancy are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01297586
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  • 2
    Electronic Resource
    Electronic Resource
    Competition between binary reactions and fusion in heavy-ion collisions at the Coulomb barrier (1992)
    Springer
    The European physical journal 342 (1992), S. 411-427 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.Cd ; 25.70.Jj ; 25.70.Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mass and charge distributions for binary reaction channels have been measured for the reactions86Kr with76Ge,104Ru and130Te at the Coulomb barrier using chemical separations andγ-ray spectroscopy. These systems span the region where dynamical hindrance to complete fusion sets in. The binary reactions can be subdivided into two components associated withi) reflection from the outer potential barrier (quasielastic), andii) reseparation after passing the barrier (complex reactions). The sum of complex-reaction channels and evaporation residues from complete fusion can be reproduced by a barrier passing calculation. The fraction of the barrier passing flux leading to reseparation increases from 26±10% for the lightest system to more than 90% for the heaviest system. The data indicate that fusion hindrance is primarily caused by reseparation shortly after passage of the barrier before Swiatecki's conditional saddlepoint is overcome, resulting in partitions close to the entrance channel configuration. In addition, for the heaviest system, a quasifission component representing somewhat less than 20% of the barrier-passing flux was observed. From the missing masses of fragment pairs we can deduce that the reseparating complex-reaction products have kinetic energies well below the fusion barrier and share the excitation energy in a way similar to the sawtooth-like curve known from low-energy fission. The quasielastic, predominantly one- and two-nucleon transfer channels, have strongly varying cross sections for the three systems despite similar effectiveQ-values. A systematics of one-neutron transfer cross sections at the Coulomb barrier is established and shown to differ considerably from the smooth behaviour observed at energies 20–30% above the barrier. The connection to nuclear polarization phenomena and orbit matching is pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294952
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  • 3
    Electronic Resource
    Electronic Resource
    Colchicine-induced stimulation of PMN motility related to cytoskeletal changes in actin, α-actinin, and myosin (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 10-18 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970250103
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  • 4
    Electronic Resource
    Electronic Resource
    Motility, cell shape, and locomotion of neutrophil granulocytes (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 47-60 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030105
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  • 5
    Electronic Resource
    Electronic Resource
    Orthokinetic and klinokinetic responses of human polymorphonuclear leucocytes (1985)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 5 (1985), S. 447-461 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970050603
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  • 6
    Electronic Resource
    Electronic Resource
    Bewertung von Oberflächenrissen mit Methoden des plastischen Versagens (1992)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 23 (1992), S. 299-304 
    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
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19920230808
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  • 7
    Electronic Resource
    Electronic Resource
    Verhalten von Chemieapparate-Werkstoffen bei höheren Temperaturen (1967)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 18 (1967), S. 112-116 
    Details
    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
    URL: http://dx.doi.org/10.1002/maco.19670180204
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  • 8
    Electronic Resource
    Electronic Resource
    Untersuchungen über die Kathodenwirkung von Eisensulfid und Mangansulfid auf die Korrosion von Eisen in dreiprozentiger Natriumchloridlösung (1981)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 32 (1981), S. 540-545 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19810321205
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  • 9
    Electronic Resource
    Electronic Resource
    Das Festigkeitsverhalten von Berstscheiben bei langzeitiger BeanspruchungVortrag, gehalten auf der Achema 1967. (1968)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 200-204 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19680190303
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  • 10
    Electronic Resource
    Electronic Resource
    Das Korrosionsverhalten von Titan in Salpetersäure hoher Temperaturen (1964)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 15 (1964), S. 741-743 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19640150906
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