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  • Chemistry  (29)
  • Physics  (4)
  • Life and Medical Sciences  (1)
  • 1970-1974  (34)
  • 1972  (34)
  • 1
    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: Im Temperaturbereich von 60 bis 100°C wird die radikalische Polymerisation von Styrol, Methylmethacrylat und Acrylnitril von α.α′-Dicyanodibenzylen ausgelöst, die in α-und α′-Stellung mit Ester-, Nitril-, Amid- oder Phenylgruppen disubstituiert sind. Bei 100 bis 110°C ist auch das α.α.α′.α′-Tetracarboxymethyldibenzyl aktiv. Vinylacetat und Vinylchlorid werden durch diese Initiatoren kaum polymerisiert.Fur die Polymerisation des Styrols wurden die Bruttogeschwindigkeitskonstanten Kp, für viele Dibenzyle und fur Peroxide vergleichbarer Aktivitat dilatornetrisch bestirnrnt. Norrnalerweise sind die Zeit-Urnsatz-Kurven rnit den Dibenzylen und den Peroxiden vergleichbar; das Tetracyanodibenzyl allerdings bewirkt nur eine unvollstandige Polymerisation.Der große Einfiuß von Substituenten in α-Stellung oder in den Phenylringen der Dibenzyle auf die Polymerisation des Styrols wird diskutiert. Dabei ist auch die Stereochernie wichtig. Die meso-Form des Dinitrildiesters ergibt eine 2.5- bis 3.5 ma1 schnellere Polyrnerisation als das dl-Isornere.Die Dissoziationsgeschwindigkeitskonstanten kd der Initiatoren wurden NMR-spektroskopisch aus der Linienbreite bestirnmt. Die Dinitrildiester sind gute Initiatoren, wahrend die α.α′-Dicyanodibenzyle rnit weiteren Nitril- oder Phenylgruppen in α- und α′-Stellung wenig geeignet sind. SchlieBlich wurde die 1.2-Addition einiger der Dibenzyle an Styrol im Ternperaturbereich von 120 bis 150°C rnit der Methode der chernisch induzierten KernPolarisation (CIDNP) untersucht.
    Notes: The radical polymerization of styrene, methyl methacrylate and acrylonitrile is initiated by α.α′-dicyanodibenzyls α.α′-disubstituted with ester, nitrile, amide or phenyl groups in the temperature range 60 to 100°C and by α.α.α′.α′-tetracarboxymethyldibenzyl at 100 to 110°C. Vinylacetate and vinylchloride show a low reactivity.The overall polymerization rate constants Kp have been determined dilatometrically for styrene initiated by a large number of dibenzyls and comparable peroxides. The styrene polymerization curves are generally comparable with those of peroxides. A notable exception is tetracyanodibenzyl.The strong influence of α- and ring-substituents in the dibenzyls on the styrene polymerization rate is discussed. The stereochemistry is also important : the meso α.α′-dicyanodibenzyls α.α′-disubstituted with ester groups give a 2.5 to 3.5 fold faster polymerization than their dl isomers.The initiator efficiency is related to the kd values, determined from NMR line width measurements. The α.α′- dicyanodibenzyls α.α′-disubstituted with ester groups are good initiators, while those with phenyl groups and nitrile groups are inefficient.Relevant to initiation and termination, the 1.2-addition of some of the dimers to styrene at 120 to 150°C has been studied with chemically induced dynamic nuclear polarization (CIDNP).
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 10 (1972), S. 851-854 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 10 (1972), S. 851-854 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 3 (1972), S. 58-64 
    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: Wear and wear Testing. The following six different wear mechanisms are briefly discussed: adhesive wear, abrasive wear, fatique wear, mechano-chemical wear and thermal wear. As to wear testing it is concluded that for obtaining a priori information on materials, laboratory testing can be quite useful, provided that the environmental conditions that prevail in practice are successfully reproduced in the laboratory. Further, it is always advisable to include in a test programme some reference materials on which practical information is available.
    Notes: Es wird eine Übersicht über die Grundprozesse, die beim Auftreten praktischer Verschleißfälle eine Rolle spielen können, gegeben. Unterschieden wird in: adhäsiven Verschleiß, Furchungsverschleiß und abrasive Erosion, Verschleiß durch Oberflächenermüdung, mechanochemischer Verschleiß und Schmelzverschleiß. Der Verlauf dieser verschiedenen Prozesse und der Einfluß verschiedener Prozeßparameter werden erörtert. Hinsichtlich der Verschleißprüfung wird darauf hingewiesen, daß man bei der Übertragung von Unterlagen aus dem Labor auf die Praxis mit Überlegung vorgehen muß. Im allgemeinen kann man nur eine sinnvolle Information über die relative Qualität von Materialien erwarten. Eine Grundbedingung hierzu ist aber noch, daß die Prüftemperatur und die Zusammensetzung der Umgebung in Übereinstimmung mit denen der Praxis gewählt werden. Außerdem empfiehlt es sich, eine Anzahl Referenzmaterialien, von denen Praxisunterlagen bekannt sind, in die Untersuchung mit einzubeziehen.
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 18 (1972), S. 670-670 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 505-518 
    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: The elastic and structural properties of polybutadiene vulcanized with magnesium methacrylate were investigated. Structural information was obtained by x-ray smallangle diffusion diagrams. Results clearly indicate that in the elastomeric network there is a random distribution of rigid particles. The elastic behavior was analyzed in terms of the Mooney-Rivlin equation. Experimental evidence for the direct correlation between elastic and structural properties is given.
    Additional Material: 11 Ill.
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  • 7
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hypoeutectic alloys of the Au-Co system were studied for use in dental castings. Microhardness and tensile data were determined for annealed and aged alloys of compositions from 0.5 to 10 at. % Co in Au. Maxima for this alloy of HK 119, elongation 23% in 10 mm, yield strength of 185 MN/m2 (0.2% offset) and tensile strength of 257 MN/m2 occurred following aging at 350°C for 15 min. The system is considered promising for use as a dental casting gold alloy.
    Additional Material: 3 Ill.
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  • 8
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Livers from five-day chick embryos maintained as organ cultures on Eagle's minimum essential medium (MEM) develop an ultrastructure similar to more mature liver cells, except for glycogen deposits and the smooth endoplasmic reticulum (SER) normally associated with such deposits. The enzymes, glycogen synthetase and glycogen phosphorylase, failed to develop in these cells. The addition of zinc-free insulin (insulin-HCl) to MEM promoted the development of small amounts of SER in the cultured cells, as well as an increase in both glycogen synthetase and phosphorylase activities. The addition of zinc-insulin also stimulated an increase in the activities of both enzymes, and promoted the development of greater amounts of SER and the deposition of glycogen, as well. In addition, both forms of insulin not only prevented the fall of total tissue protein which occurs during organ culture on MEM, but also stimulated net protein synthesis in the explanted liver (Benzo and de la Haba, '71).
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 387 (1972), S. 61-71 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: By adding acetyl halide to solutions of copper(I)acetate in mixtures of acetonitrile and acetic acid, highly pure copper(I) halides can be prepared. These form with pyridine and alkylpyridines (= L) yellow or greenish yellow compounds of the formula Cu(L)3X. Colourless compounds of the formula Cu(L)X can be obtained by thermal decomposition of these compounds. All these compounds exhibit an intensive fluorescence of different colours. Some compounds of the formula Cu(L)X change at low temperatures reversibly the fluorescence colour. It is proposed, to use for this phenomenon the term ‘Fluorescence Thermochromism’.
    Notes: Durch Zugabe von Acetylhalogenid zu Lösungen von Kupfer(I)-acetat in Acetonitril/Essigsäuregemischen sind reinste Kupfer(I)-Halogenide darstellbar. Diese bilden mit Pyridin und Alkylpyridinen (= L) gelbe bis grüngelbe Verbindungen der Zusammensetzung Cu(L)3X. Durch thermische Zersetzung können daraus farblose Verbindungen der Zusammensetzung Cu(L)X dargestellt werden. Alle diese Verbindungen zeigen eine intensive Fluoreszenz der verschiedensten Farben. Einige Verbindungen der Zusammensetzung Cu(L)X ändern bei tiefer Temperatur reversibel ihre Fluoreszenzfarbe. Für diese Erscheinung wird der Begriff ‘Fluoreszenz-Thermochromie’ vorgeschlagen.
    Additional Material: 3 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 389 (1972), S. 215-219 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Es wird über Herstellung und Eigenschaften von NiII- und CuII-Komplexen mit der SCHIFFschen Base „BAPE“ aus Acetophenon und Äthylendiamin sowie über gemischte BAPE/Acetylaceton-Komplexe berichtet (Formeln I-V s. Abstract). BAPE wirkt dabei als zweizähniger Neutralligand. Die Komplexe wurden durch Elementaranalyse, Elektronenspektrum sowie durch magnetische und Leitfähigkeitsmessungen charakterisiert. Für MII(BAPE)Cl2 wird pseudotetraedrische, für [MII(BAPE)(acac)(H2O)2] ClO4 tetragonale Struktur abgeleitet (MII = Ni, Cu). Der Komplex [Ni(BAPE)(acac)]ClO4 erwies sich als quadratisch-planar.
    Notes: Preparation and properties of the following NiII and CuII complexes of the Schiff base derived from acetophenone and ethylenediamine (BAPE) and also of the mixed NiII and CuII chelates with BAPE and acetylacetone (acac-H) are described: In each case the Schiff base, BAPE, acts as a neutral bidentate ligand. The complexes are characterised by electronic spectra, magnetic susceptibilities, conductivities and elemental analyses. Pseudotetrahedral structure is proposed for M(BAPE)C12, while tetragonal structure for [M(BAPE)(acac)(H2O)2]ClO4 (M = Ni and Cu). The complex [Ni(BAPE) (acac)]ClO4 has been found to be square planar.
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